Just upgraded from X2 Essential to X3 Producer.  I can't find any documentation that tells me how to record individual drums/cymbals in an AD2 kit to their own tracks.  I'm not using loops or beats - I'm step recording and want to record a full drum pattern one drum at a time (kicks first, snare, followed by cymbals, etc.).  Anyone in the same boat that can tell me how this is accomplished?  

The "normal" way of doing it is not recording each kitpiece MIDI on separate tracks, but to have all MIDI on one track and have audio outputs through separate tracks. If the MIDI is on separate tracks you'll have a hard time editing, say breaks, if every hit is on a track of its own. 
There should be no problem step recording one kitpiece at a time on the same track by using sound on sound recording option. And that sound on sound possibility goes with all recording, MIDI and audio, and has nothing to do with AD specifically.
 
When inserting a softsynth in SONAR you get a pop up window which gives you the option to choose one stereo output track or separate outputs for each kitpiece. 
 
 

I am one of probably a very few who ALWAYS creates a separate midi track for each kit piece. All tracks are named, just as you would label an audio track. Then all my midi drum tracks go in to a Drum Kit folder. The reasoning behind this is it's much easier to control each kit piece and track down any problem very quickly and easily when dealing with one track for that kit piece. If I have a problem with the velocity is a little too hard on the snare for an entire verse, simply open the snare track, mark the verse and run the scale velocity cal. Otherwise, you would have to search thru all notes for the whole kit! Then deal with setting up the edit filter. Yikes! Deep editing could take a while.
You still have the ability to break those tracks out in to separate audio. Having the separate midi tracks just seems to give you a very concentrated view of what is actually going on with the individual drum pieces.
BTW, after you have all your tracks finished and ready, you can always merge the tracks together on to one track if you like. I just choose to leave them separated in the folder.
There are a couple of ways to do this.
You can do individual tracks for each kit piece or you can have 1 track for kick, 1 for snare, 1 for ALL the toms, 1 track for hi-hat, or 1 track for all cymbals. I prefer a track for every kit piece. This even goes for latin percussion. I have one midi track for every percussion instrument and those are kept in a Latin Percussion folder.
Just make sure that all your midi tracks outputs are set for the drum vsti. All on the same channel. I don't know if you are using piano editor or notation editor. I use notation. That is a sticky point with Sonar because the notation editor is very, very weak but it is good enough to get drum tracks put together. Let us know how you are inputting your tracks and maybe I can give some more advice.
I know this whole process looks a little overwhelming but it has saved my #$%& more than once!

I use the track template for addictive drums which puts each drum on its own audio out. I then insert a midi track and record or drag loop to that. I personally prefer one midi track as I can instantly see how all of the combined parts work together in the piano roll view. If you want to run a CAL script on any notes within the prv, you can just right click and drag over any notes you want and run the script which will only affect those highlighted

Wizard is right about the use of the piano roll. I said before, I use the notation window with all the tracks assigned to percussion staff. I then highlight all the tracks if I need to see all of them. You can choose individual tracks from the staff view when you want to fine tune the display to one or two tracks. It's just easier for me because I am a classically trained musician that reads and writes notes. Bad habits are hard to break! LOL!

Lol Sidroe, I am classically trained too but the notation is so painful to use, I just can't face it. I do use sibelius if I need to really see what I'm doing though and just import the midi file into sonar

I have a couple of notation programs as well. I have even gone so far as to use Notion 4 Re-wired in to Sonar sometimes. I agree the notation or staff view in Sonar is pretty dismal. I generally use the staff if I am writing drums or I will use the split notes to tracks cal if the midi came from somewhere else. All the other tracks are played in realtime once the drums and bass are clicking.

Sidroe
I am one of probably a very few who ALWAYS creates a separate midi track for each kit piece. All tracks are named, just as you would label an audio track. Then all my midi drum tracks go in to a Drum Kit folder. The reasoning behind this is it's much easier to control each kit piece and track down any problem very quickly and easily when dealing with one track for that kit piece. If I have a problem with the velocity is a little too hard on the snare for an entire verse, simply open the snare track, mark the verse and run the scale velocity cal. Otherwise, you would have to search thru all notes for the whole kit! Then deal with setting up the edit filter. Yikes! Deep editing could take a while.
You still have the ability to break those tracks out in to separate audio. Having the separate midi tracks just seems to give you a very concentrated view of what is actually going on with the individual drum pieces.
BTW, after you have all your tracks finished and ready, you can always merge the tracks together on to one track if you like. I just choose to leave them separated in the folder.
There are a couple of ways to do this.
You can do individual tracks for each kit piece or you can have 1 track for kick, 1 for snare, 1 for ALL the toms, 1 track for hi-hat, or 1 track for all cymbals. I prefer a track for every kit piece. This even goes for latin percussion. I have one midi track for every percussion instrument and those are kept in a Latin Percussion folder.
Just make sure that all your midi tracks outputs are set for the drum vsti. All on the same channel. I don't know if you are using piano editor or notation editor. I use notation. That is a sticky point with Sonar because the notation editor is very, very weak but it is good enough to get drum tracks put together. Let us know how you are inputting your tracks and maybe I can give some more advice.
I know this whole process looks a little overwhelming but it has saved my #$%& more than once!

sidroe - that's what I do. I would add regarding my approach that I have a "blank file" which is a Sonar file with all of this set up. I start from a copy of that file and just start adding the music / musical ideas to it.

I do the same thing as Sidroe. Except, I write the drum track in one midi track then I use a cal file to split each note to it's own track. I received a cal file called "drum split and name",  which does what it says. Though it used the GM (general midi) format of writing for drums.
 
I've been using Finale to write all my parts out but lately, I just can't stare at a white screen anymore so I am learning to use the PRV since it is not so painful to look at. I just think it's not as intuitive.

Gosh, I don't feel so alone anymore! HEE-HEE!