I have the Alesis DM10 Studio set and the brainbox will not allow me to change the midi notes that the hi-hat uses so I use eDrum MIDI Mapper to remap my Alesis notes, output to a virtual LoopBe1 midi cable and use the virtual midi cable as an input in Sonar. (I also disabled the Alesis as an input in Sonar since the virtual midi cable serves that purpose)
This eDrum MIDI Mapper allows me to remap the entire Alesis set to the midi notes I want/need for backwards compatibility to drum tracks that I have recorded in the past with Addictive Drums' early note/articulation keyboard mapping.
I don't see any reason why this method would not work for Session Drummer or any other drums soft synth.
As a matter of fact, I use this method with Steven Slate Drums sampler as well.

What I was saying is it's not the Sample player or the DAW, but the sfx samples that seem to contain extra data that responds to things like rim shots, hi hat and ride cymbal bell tones. 
A lot of the samples are just MP3, Flac or Wave files.  You notice in Session drummer that most of the notes play the same 8 sounds loaded into the kit. There is no rim shot etc. But I find using some of the sfx samples yield the extra sounds I'm getting from the brain. Read up on sfx and you'll see what I mean. 
Session drummer works fine for me IF I use some samples. This is very few of the ones that are in the library with Sonar 8. 

gustabo
I have the Alesis DM10 Studio set and the brainbox will not allow me to change the midi notes that the hi-hat uses so I use to remap my Alesis notes, output to a and use the virtual midi cable as an input in Sonar. (I also disabled the Alesis as an input in Sonar since the virtual midi cable serves that purpose)
This eDrum MIDI Mapper allows me to remap the entire Alesis set to the midi notes I want/need for backwards compatibility to drum tracks that I have recorded in the past with Addictive Drums' early note/articulation keyboard mapping.
I don't see any reason why this method would not work for Session Drummer or any other drums soft synth.
As a matter of fact, I use this method with Steven Slate Drums sampler as well.

Thanks for this. Is it easy to set up?

Very easy if you take your time. All the work that you're doing is in eDrum MIDI Mapper so you're not messing with your brainbox or Sonar.
eDrum MIDI Mapper is donationware which is 100% functional but out of development. I did contact the author and not many people paid for it so I sent him $50 because the program had been a godsend to him. He emailed me back thanking me and let me know that the $50 I had sent him was more than all his previous income from the program before he stopped development. Since the program needs to be running while using Sonar, I asked him about adding a "minimize to tray option" but he said he doesn't know if he even knows where his source code is anymore.

One thing to keep in mind, since there is no standard for note designations that everyone follows, a C4 in one program may be a C6 in another program.
This inconsistency may cause some hair pulling but once you set everything up, save it as a preset in eDrum MIDI Mapper and you're good to go.
Using saved presets, you can create and save mapping presets for use with different drum softsynth mappings.

Thanks gustabo, I'll check it out.

Make sure you haven't got the kick and hi-hat pedals reversed.
The hi-hat pedal appears to be the standard Alesis momentary contact on/off switch. It shouldn't be sending CC messages. Unlike most Alesis kits, the kick and hi-hat pedals look to be visually identical.
If you have the kick pedal(one note, velocity sensitive) connected to the hi-hat port, that would explain open/closed as the same note, combined with data that the brain is most likely misinterpreting. Reading note 46 would make sense, as nothing is triggering the variables that would make it read otherwise.
You should be seeing note 46(open), note 44(pedal) if you hit the hi-hat pad as you step on the pedal, and note 42(closed).
Your kicks are probably all being triggered at 127 as well.
hth

Unless they have been labelled wrongly by Alesis, the pedals are connected correctly. It produces note 44 (pedal) ok but open and closed are note 46 with the cc4 message.

I also have the alesis DM lite and a hi hat issue. I'm using sonar 5 producer an SI-drums everything works well except the hi hat it does open an pedal but not closed ! Really doing my head in! I'm glad I'm not the only one, an hoping that it's easy to resolve. I shall post my issue! Fingers crossed!

My hihat pedal has a big honking CONTINUOUS label on it but actually it's just a momentary controller. We won't be able to play closed hihats with it, ever.