I shouldn't expect it to void the warranty. It's pretty simple if you have the same type of keys - they literally just pop off if you pull them up correctly. The keys can be bought from eBay - but they aren't cheap.
A guy on these forums gave his white MacBook a black bezel not too long ago. It looked awesome and I sooo want mine to look like that. I'm just way too scared to mess with its display like that.