Really, you do not need to be promoting something that is not yours. Besides, why not make your own forum and make it how you want it, and become admin of that? That is way easier!
I'f its ur site and you're friends taken admin from you just go into PHPmyAdmin and change you're group value in username to the same as you're freinds then change his to what you'rs was. I dont think by advertising here you're going to get 150 members.