anything is possible with enough creativity, wire cutters and spare wire. personaly i like my cruise control buttons. id feel like an *** pressing coast and having the volume go up. kinda sounds cool at first but idunno. if you could--would a second cruisecontrol switch pod fit on the otherside of the steering wheel upside down? mount it upside down o nthe other side and get some stencils for the lettering. a + and - would do fine.
do you have an after market or stock HU? it would involve opening the headunit and reading a scematic diagram to solder in overriding controls to the volume attenuater. my spelling sucks. sorry.