Edit <FishEye home directory>/syntax/filename.map and add the file extensions using the following as a guide. For example, to add module, install, and inc as extensions to be highlighted similarly to PHP files and htm to be highlighted similarly to HTML files add the following four lines to the end of the file:

"**/*.module" php.def
"**/*.install" php.def
"**/*.inc" php.def
"**/*.htm" html.def

 Fisheye/Crucible needs to be restarted to have the changes take effect.

Related

Defining your own syntax highlighting in Crucible or Fisheye