Photoelectric has written a good guide.
http://geekhack.org/index.php?topic=44191.0I have only painted (poorly) a F122 plate, but I blame the paint (rustoleum in "hammered" finish). I have better paint now and will be using it after I make up a new mat.
Painting cases is not for everyone. Certainly not for me. That said, case colour never really bothered me. I want to see the inside of this keyboard, so I can see how the OAK FTM switches were mounted in the case, but I dont want that info enough to actually buy the KB at this price.
Recently, I lost an auction for one of those AT&T model Ms. The main reason I want one is so I can study it more fully (and 'cause I don't hate italic-print keycaps like the rest of you guys seem to) and I collect odd or interesting IBM keycaps.