Open up this directory (the bold parts will change on your computer):
C:\Documents and Settings\Dan\Application Data\Mozilla\Firefox\Profiles\5cnv17re.default\gm_scripts\fr_tree_viewer
Application Data is a hidden folder so you may have to manually type it in the address bar to open it.
From there, you will see the fr_tree_viewer.user.js file. This is the file you can open up and edit.
Thanks. I will try it.