Just wanted to share this in case it helps anyone.
I noticed the stock Google 4.2.1 rom on my Galaxy Nexus connected fine to eHRPD and LTE, but when I flashed CyanogenMod 10.1 I could only get EVDO. So I used an APN backup utility to get the proper APN settings from stock and created a recovery-flashable zip file. This also sets the Ting MMS URL.
This fixed both LTE and eHRPD for me.
The zip file is attached to this post. Flash it over an already-installed Cyanogenmod rom, and again any time after you flash a rom update. I don't know if these APNs will work for other LTE devices besides the Galaxy Nexus, but I suspect they will. I've only flashed this zip from TWRP, so it may or may not work with other recoveries (ie: Clockwork).
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).
New version attached for Android 4.3. Credit to @ poo706 for figuring out the new APN version number change. (Now removed. Use version 3 zip.)
New version 3 zip, also updated with CM Sprint APN revisions. Unless you're running an older CM, use this one.
**edit March 14 2014**
Since some of the latest CM nightlies, I'm having better luck with flashing the zip from this post:
Thanks to @Deante Flood for that. His APNs have some additional lines for bare CDMA (non LTE/eHRPD).
Make sure you do a "Reset to default" in the APNs screen afteward. (Voice Dialer -> Say "open apns". Or under Settings -> More -> Mobile Networks -> Access Point Names on some devices).