Wavey-
Don't look at the CCF files as skins. The files are really more similiar to a complete application, or a complete remote in itself. The RC500o is simply the platform that these applications run on.. A CCF file has not only the look and feel, but IR codes, macros, etc.
I suggest you read the Pronto FAQ on this site to learn more. Here's the link
[Link: remotecentral.com]