We currently use clearcase on a project, and there is an HTML file that was generated with clearcase that contains all of the filenames of the files that were included in a
I am not sure about the exact HTML file you are referring to. Do you have an example of its name, and of its content? If you edit your question with those data, I will be able to add to this answer.
But anyway, if that file is not generated directly by ClearCase, the solution remains to parse a cleartool find command (see also Additional examples of the cleartool find command article)
cleartool find . –version "lbtype(MY_LABEL-1.0)"
and to build your html file with, for instance, a Perl script.
You could even add this action into a ClearCase sub-menu entry, like illustrated in the ten best scripts article.