Help Using pldoc_process:doc_comment/4

I'd like to process comments for files without worrying about
compiling them or otherwise creating side-effects that may be
problematic.  The purpose would be for command completion hints.

At first, I thought I could use read_clause and/or read_term.  It
seems that 'pldoc.pl' needs to be loaded beforehand but I can't seem
to figure out exactly how the state is handled and why I can't just
run a file through read_clause and then be able to call
pldoc_process:doc_comment/4.

Any suggestions would be appreciated,
--
Ian Tegebo