I run Lupohirp's cm9 testing version and have working data on my p-509 on t-mo,
I'm surprised you are on the new baseband since t-mo never released gingerbread for our phones, but I rooted a long time ago, and have flashed a bunch of roms, so OTA updates aren't coming my way ; p
I got it to work with a file called PatchOldBB.zip (181.54 KB) which I think I got from NightlyFourE_v3.4 rom page.
I know it might not apply since you have newer BB but I thought I'd share my experience anyhow on the off chance it helps.
(don't forget to disable "signature verify" in recovery>other)
Thanks Fred..
I'm sure some of us will use this info. Not having data sucks. Would you be able to link us up to that flash?
Sent from my SGH-T959 using XDA