Kinda late in on this but would like to address a couple of points.
First off, MMS remains a service provided by your carrier and not RIM. You do however need two service books as these are required to enable the client and provide the transport settings. These service books do not originate from BIS however, but instead the RIM relay.
If you are short of these service books and you are provisioned and active on the relay then re-register via HRT rather than sending BIS service books from your carriers BIS web self serve.
As was mentioned elsewhere, once you have the required service books the service will work whether you are active on the relay or not. I would guess the T-Mobile oojamaflip simply creates the required service books.
cheers
Worm