Actually, the method described on appleiphoneschool didn't work for me, but someone said thatbdownloading the MMS & Tethering settings from Sinful repo worked.
I had tried this a few days ago, and it didn't work so I uninstalled it. I decided to give it another shot, and it works flawlessly.
Well, almost flawlessly.
My voicemails aren't really going through, and I've had some weird interaction with sending emails while on WiFi, but that's about it. As cool as it is, I need voicemail to work a bit more than MMS, so I may uninstall, but I guess we shall see.
I'm in NYC by the way.
Also, in my Cellular Data Settings, my VVM settings are configured for the acds.Voicemail setting, so everything SHOULD hypothetically be fine, but the issues I listed above are still issues.