Bookmark locations on the memory stick?

I have tried to search for this but did not find anything. I apologise if this is a repetition.

Is there any way in Firefox to add a bookmark for a location on the memory stick? Obviously the main issue is that the mount point for the memory stick varies, so there is no fixed path?

An alternative would be the ability to add custom shortcuts to the portableapps launcher, to allow you to launch the portable firefox and thus pass a relative path in the command line to the document on the memory stick.

I would appreciate any suggestions.