if its external, the problem is probably not the vibration noise. its the fan noise from the pump.. the mousepad may help a little, but it wont kill it. you can do foam in your cabinet, and depending on what foam you use it will help significantly. but thats depending on the foam you use.. if you use real studio foam (auralex) it will make a huge difference, but if not it probably wont. what kind of pump is it? genx mak4? the titanium series pumps are completely silent, to the point where even if your cabinet is open, and you are sitting on the floor in front of it messing around under there, you will have to touch it to make sure its running.
