How are your skins overwritten? I don't quite follow that one. In a forum integration we simply map the correct variables from the forum used for the same similar class in our templates that we use
These variables would not change in the forum that I know of unless your using some non standard product that we do not integrate with in the first place on a style level. All
vb and ipb and phpbb and threads among others that I know of have a set standard meaning tcat is tcat in every style blah blah blah.
I have come across in my time products that have different class calls for different templates but we do not support those products on a style level as a direct result.
We can think about being able to define them in a later update. It is easy to make a database table and form to do so the main issue we have would be excluding and including what forum which variables etc which can get extremely complicated with the number of forums we support