I'm having a similar issue with Omni. I flashed it last week and while it temporarily sees Verizon, it doesn't connect. I saw something on the ROM thread under developers (and so far I haven't searched through any other threads for resolutions) but I might try what was suggested there to see if it is the solution we're looking for. I'll post back here if I find something actionable.
I'll keep searching for a more simple process and post if I find it.
I saw that, having the same issue myself. I haven't tried it personally, but I remain skeptical about it working. Even following the steps, after the bigPart step, the tablet is essentially wiped clean, no OS, no radios, nothing. Without an OTA update from verizon (which we can't get via a custom rom) the modem baseband won't download and update to provide 4G data (I have an upgraded MZ600 Xoom).
So basically even if I followed all those steps, I still wouldn't have 4G data unless I could get the new baseband software installed...
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