If you want to clean UNDER the keys, buy a long toothbrush (the one who's like a gun cleaner, intended for ppl who uses tooth devices).
If you want to clean the keys, gently pry they off with a small flat screwdriver, anotate the keys positions, then rub them with iso OR acetone.
Put them in a cloth bag and toss it into a dishwasher machine is a good idea, too (don't worry, they don't melt with the hot water). ;-)
