I just wanted to share this in case it helps anyone else with a GNex on Ting service.
I noticed the stock Google 4.2.1 rom on my GNex connected fine to eHRPD and LTE, but when I flashed CM10.1 I could only get EVDO. So I used an APN backup utility to get the proper APN settings from stock, tweaked them to work with CM, and created a recovery-flashable zip file.
These APNs fixed both LTE and eHRPD for me. It also sets the Ting MMS URL.
The zip file is attached to this post. Flash it over an already-installed CM rom, and again any time after you flash a rom update. I don't know if these APNs will work for other LTE devices on Ting besides the Galaxy Nexus, but I suspect they will.
Uninstall is as simple as re-flashing your CM rom, or restoring your original "/system/etc/apns-conf.xml" file with a root file explorer app (if you saved a backup before flashing this).
Another thing I did was set eHRPD to "On" under *#*#3282#*#* -> Edit -> Others/More, though I'm not sure how much difference it makes.
The zip here:
... fixed my 3g issues in the latest CM11 nightlies. He's got some extra lines for bare CDMA (non-LTE/eHRPD).