Hi, if you are using the pads A1-A8 as part of ACT, I'm afraid you cannot change the note numbers assigned by default. In that case you'll either have to change the mapping of your drum kit within SD3/SD2, or use Sonar's drum map.
On the other hand, if you exclude A1-A8 from ACT, you can assign desired note numbers to the pads using the A-Pro Editor (I haven't done it myself but I think it's possible). The A-Pro PDF manual explains how to assign note messages so you might want to check it out.