Today jonwil announced over at the rct2.com forums that he was able study the ovl file codes used in RCT3, and changed the texture on an object. The thread is HERE. Take a moment to check out the images posted by dagsmatt...
While this might not seem like much, a mere baby step perhaps, but it represents a huge first step towards the possibility of changing the skins on in-game objects, and perhaps down the line adding user-created objects to RCT3.
Once again it seems to me that members of the community are the ones who have done the work to improve the game.
Hat's off to jonwil!