For help with general CEGUI usage: - Questions about the usage of CEGUI and its features, if not explained in the documentation. - Problems with the CMAKE configuration or problems occuring during the build process/compilation. - Errors or unexpected behaviour.
The situation is the same as for any other engine; you'll need to write a renderer module to interface the two libraries. Depending on how - or if - RW exposes any access to the underlying API, you might be able to use the existing GL or D3D renderers to 'hook in' at a lower level, though there would likely be various problems to overcome to synchronise things correctly.