Generally do you cut/melt the little plastic nubs off or drill the new clip-ons?
I generally cut 'em off, but whatever you want to do is fine. Any sort of tape or shim will work just fine if you're concerned about the controls rotating on the bars. I've used Duct-tape, electrical tape, bits of rubber, thin metal with a liquid gasket, or whatever I have lying around that looks like it'd work well. Other times, they clamp down just fine on their own.