I was reading that Lucas originally wanted Orson Welles for Vader which would have been very cool, so what if you dubbed Vader with The Brain from 'Pinky and The Brain' as that's a perfect spoof of Orson's voice.
After all what does Vader do every night? "Try to take over the world!"
Handily P&TB did a SW spoof episode that could be mined for SW specific words...