....some keyboards ..have no Atertouch function but the user can assign cc131 to a programmable slider.......
My keyboard has Aftertouch, but it is activated by pressing a key (of course). Since I am NOT playing the notes, - all comes from MIDI - I have to add aftertouch with CC131. How can I do that while the max value for CC# = 126? Apart of course from drawing in Sonar?
But what's wrong with doing it that way? Choose Aftertouch, and swoop the values in with the grid turned off while holding down the CTRL key. My keyboard doesn't have Aftertouch, and so I draw it in all the time - Pretty painless process.
And if you have a programmable MIDI control of some sort, on your keyboard or some other device, you can ask for any CC# you want, even above the standard MIDI spec. That's if you want to try the CC131 approach.
"...using some sort of a wheel/slider makes it a bit easier..."
OK - I just tested on my humble little keyboard to make sure I was right. I have one programmable wheel - I type in 131 - and that's what I get. As I said earlier, you shouldn't be limited by your controller to only go up to 126.