nsHelperAppDlg.js

I dont know if this is the right newsgroup for this but I am trying to 
dynamically register and unregister nsHelperAppDlg.js.  I can see at the 
end of the file it has all the info needed to register the module.  I 
don't plan on needing it register all that often, but I don't want to 
just delete it.  Specifically, I am planning on setting an option in 
prefs that allows that file to be registered or not and I want to do 
this via a js file.  If anyone could help me out it would be greatly 
appreciated!

Jason