http://www.pentax.jp/japan/support/customize.html
(in Japanese)
Update (8-5): The above picture link is dead because Ricoh has changed the domain name of their website. I just won't bother to correct that as it's the sole fault of Ricoh!
Well, the main point of those RP cameras is now colours, not the colours of the images they produce, but the colours of the camera shells! Well done, Ricoh! >:-(