Just to clarify a few details, it is possible to remove the keyboards in the retina display machine, but is not the greatest job to undertake... They look like they are riveted, as dan said, but they are actually metal plugs (they function a bit like a snap rivet) so are removable. You have to pull the keyboard fairly hard, then each plug will pop out. You will then need a keyboard screw set from the 15" Unibody MacBook Pro machine for when you replace the keyboard, as the screws are able to drill their own thread into the aluminium. (just be careful you dont thread the screw heads when you do this)
The difficulty after that, is actually finding the keyboards on their own... its no easy task, thats for sure. Apple dont sell them separately (in fact, they sell the top case unit with the battery, and trackpad as well, which makes it much more expensive)
The other details Dan mentioned are clear enough. I use isopropyl alcohol, cotton buds and a cloth to clean liquid damage, but the residue is often difficult to fully clear up, and if its slid under components, it can corrode with time, causing an assumed fully working machine to slowly degrade with time.