I did this to my (admittedly shocking)
Laptop Keyboard recently. What I did was:
1.Have a cloth and dustbuster ready, it could be scary (depending if you eat at your PC, length of time since last clean, pets etc.)
2.Take a photo of the keyboard layout if you have a complex keyboard (mine was a G15 so there's lots of special keys).
3.Using a screwdriver carefully pry the keys up. I recommend starting at the spacebar, as you can see how the keys are attached (usually a plastic clip and metal bar). It's easy to break the plastic clip (I did twice) but it hasn't really affected my
Laptop Keyboard.
4.Clean it out!
5.Put the keys back into their positions.