Usergroups based on post count?

[Prohibit]

Is it possible to have vBulletin automatically add a user to a usergroup based on their post count?

I have user ranks set up (admin/moderator/donators) etc, but I would like to set up images for "Junior Member", "Senior Member", etc as well.

I did search this, but maybe not good enough.

Sorry if the answer has already been posted.

Thanks! :)