Split a VB6 IE toolbar plugin into 2 parts, and add Firefox toolbar support. (repost)

I have a Vb6 app that is an IE plugin and sits in the toolbar. It was originally written with the toolbar code, and the main logic for the app, all in one DLL. I would like to split this app into two pieces. The toolbar logic, and the main logic. Once this is done, I would like to have a toolbar plugin for Firefox as well that does the same thing. IE Plugin > Main Logic DLL Firefox > Main Logic DLL More info available on request.