The pressure pads are completely configurable on the Axiom controllers. You can assign them to either notes or to CCs. Refer to the user documentation for programming the pads (IIRC it's kinda obtuse, so you'll want to save it as a preset so you only have to do it once!).
To discover the default note assignments, just record to a MIDI track while hitting the pads and see where the notes land. You can then elect to skip programming the controller and use a drum map to reassign the notes. Consult the SONAR help file for instructions on creating a drum map, which is actually easier than programming the keyboard.