I would really, really like to use my new PC40 Mk2 as a control surface for Sonar X3e.  Not only that, but also my new APC Min and APC Key25.  Unfortunately, they are bus powered by Ableton Live, but if someone can hack the interface, I'll buy them a beer....
 
They work SO well with Live....

Hello,
 
Not sure if this helps but I am using an Akai Mpd26 with X3 with no issues.  Transport, buttons and Sliders.  Using cakewalk generic surface and the MPK49 as a template. IHTH...

The latter two should work fine going the route Lunatech indicated.  The APC 40 could probably work, but it is so geared towards Ableton that I'm not sure you would get much benefit from it with Sonar

I tried the APC Key 25 using the above, and the keyboard works with VST synths.  But the buttons and pads also work to key notes, not as a control surface.  (Actually, I have a VS-20 and a Tranzport hooked up to control Sonar, so it's not that big a deal for me.)
 
Thanks much for the tip....

Pads/buttons on all simple controllers can produce "NOTE ON/OFF" MIDI events, exactly the same events as normal keys (but on different MIDI Channel). Control Surface Plug-in is what can change the result of the button/pad/key press from natural behavior (note delivered to MIDI track -> VST synth) to some "Control Surface" action (command, transport, etc.).
 
You can try cakewalk generic surface or ACT MIDI plug-ins. After they "learn" (not ACT learn!) some button, this button will be used as a control (original note event will be "intercepted" by plug-in and no longer delivered to VST).
 
Otherwise you can "remote control" most buttons in SONAR itself (like mute, solo, etc.). Right-click on the corresponding SONAR button and select "Remote control..." for configuration.
 

I should mention that for Ableton Live, the APC Mini and the APC Key 25 have turned out to  be a disappointment, since the shift-arrow functions increment the matrix only by scene/track, not by the matrix as a whole, which is totally useless (and inconsistent with all other controllers, including both APC40's, Push, and the Launchpads).
 
I don't know who was responsible at Akai for specifying this functionality to Ableton, since it is described that way in the documentation (which I assume was written by Akai), but it has to be changed for these units to be useful in any real way...  At present, there is no way to change banks with these units, except by pressing the arrow keys the exact number of the dimension of the bank... this is crazy for those who have created their sets (8x8, or 5x8) in other controllers... (e.g., the APC40 Mk2 works as expected)

Here's a trick I learned with the APC40... it has two distinct controller modes, Ableton and Generic.  The problem is there's no good way of switching between them, but you can do this.... with your APC on, open Ableton and remove the APC from your MIDI devices within the Ableton preferences.  This action usually works to reset the APC into its generic mode.  Close Ableton and go back to work in Sonar... the APC should now behave as any MIDI controller would, sending note ON/OFF data for the grid, and sending appropriate CC data for the encoders and faders.  The transport should work as well.  I've found the APC to be a perfectly usable controller within Sonar, although I never use the grid anymore.

Great idea, I'll try it.  Might work for the APC40 MkII, APC Mini, and APC Key 25 as well.  I'll try it and report back... 
 

Skeptrix Digital
Here's a trick I learned with the APC40... it has two distinct controller modes, Ableton and Generic.  The problem is there's no good way of switching between them, but you can do this.... with your APC on, open Ableton and remove the APC from your MIDI devices within the Ableton preferences.  This action usually works to reset the APC into its generic mode.  Close Ableton and go back to work in Sonar... the APC should now behave as any MIDI controller would, sending note ON/OFF data for the grid, and sending appropriate CC data for the encoders and faders.  The transport should work as well.  I've found the APC to be a perfectly usable controller within Sonar, although I never use the grid anymore.