In Dom's Absence, I will answer on behaf of JEDI-SDL

The JEDI-SDL suite contains a sdlstreams.pas unit which wraps up the TStream and SDL_RWops.

Basically you can use the functions in that unit to create the SDL_RWops from a TStream, TMemoryStream, TFileStream, TResourceStream etc and pass that to the appropriate SDL_Load function.

Personally I have written a system which will allow you to load resources from a compressed archive and load them directly into SDL. e.g use IMG_LoadRW to load the resource from the compressed archive file.

Unfortunately it's an integral part of my InfinitEngine which is still in development. sorry