Why not just switch to IPB completely rather than continuing to rip and copy ideas from it. They are stopping support for this version of vBulletin anyway and version 4 is a waste of time. I'm not sure if your aware but one of the staff members (and I'm pretty sure it was elj for reasons I won't go into) had an IPB Version of WJunction on another domain. It worked great, looked cool, had loads of great features and IPB comes with a great mobile skin already so only a small bit of colour change would be needed.
I second that, and just want to emphasize on the whole "this version is reaching eol".
I've been seeing more advanced webmasters switch over to ipb in the last 6 months and there's a reason for it.