The theorem module uses the amsthm package. If you check check section 4.3 of
the manual for ammsthm, you'll find the syntax for the \newtheoremstyle command.
You will want to hack the include file to put code in the preamble creating new
theorem styles with names you supply (e.g., myThm) and then replace any
instances of \theoremstyle{plain} with \theoremstyle{myThm} (or whatever
modified style you want for that type of environment)./Paul
