the themes are actually quite editable.
as a matter of fact, you can edit the look and color of them from within the admin CP. and im not talking about the way phpBB does it, you can actually edit EVERYTHING.
the only thing youd have to do outside the admin cp is create the base of the themes. once you get that, .tar it and upload it, then use the import feature in the admin cp and it brings out everything and puts it where its supposed to go
and modding is VERY easy compared to phpBB...and phpBB is easy to mod :P
mikem, maybe ill set up a test invision board at a subdomain for you, you can fool with it