You could open the racemenu and close it in a frame, and maybe hide it with a flash or something when the player changes form. Worth a try.
I don't think it's possible to force the player into a new race though... he has to change race voluntarily, so also has to see what he's picking
Not 100% sure on this all though, haven't really been following the latest OBSE functions... though I'm pretty sure someone would already have made it if it's possible through this method
Might wanna take a look at http://tesnexus.com/downloads/file.php?id=33080 though, and more specifically, the videos on that mod.... there you can see player changing form to a wolf and also keeping HUD. The black screen during transformation is optional (depending on whether you have OBGE or not I think) if I'm not mistaken, so it's not used to hide anything.
Haven't checked this mod myself yet since my PC with Oblivion installed on it is broken and new PC didn't arrive yet