If these buttons are e.g. button 4 and 5, you may be able to map them to other functions.
Try putting this in a file in the scripts folder e.g. "test.tcl"
Code:
puts "test.tcl"
bind <Button-5> {puts "hello from button 5"}
Watch for test.tcl in the console when AC3D starts, to make sure the script ran. If pressing another button on your mouse prints something in the console, it's possible to map this event to another button - let us know.