In response to another similar question, I wrote this little utility script for inspecting sub definitions and sub calls in perl source code. It's more than a one-liner, but not more than a couple hours worth of work (so, don't expect it to be really thorough -- but at least the explanation that comes with it is "accurate", I hope).

I would be interested to find out which modules you want to try it on, and whether it is helpful from your perspective.