Whoah... I don't think that's ever been done. Very interesting, but are you sure you want to do this? Installation wizards are designed to only show one page at a time, with the Next and Back buttons allowing the user to go back and forward. From a user interface perspective, adding tabs to this model would be a questionable choice...
As for how to do it, no idea. If tabs are standard window elements maybe you can create them using nsDialogs. Perhaps someone else has some pointers.
that's not even a true tab as it's part of the ribbon ui. but really, if an installer needs to have tabs, then the layout of what you're trying to do is completely wrong.
-daz