Filemaker scripting/Applescripting/Automator

I feel like I'm missing something simple and I'm hoping a fresh perspective will bring to light the answer...

Here's the workflow: Button is clicked in FileMaker 7, runs "email" script in which addressee, subject line and Message text are all specified coming from FileMaker fields.
All works as it should, but... I want to attach a file also.

FileMaker has an option to attach a file but it wants a specific file path. The files to be attached will be different for each record.

So, what I'm looking for is:

a) FileMaker to ask what file you want to attach
or
b) An Applescript or Automator task that opens the unsent message in Entourage's "Drafts" folder within the "Folders on my Computer" folder and prompts the user to browse for a file to attach.

Any help or suggestions would be much appreciated, even if it's of the nature of "it's not possible."