Credit goes to MopedRyder for this version of CarbonRom to work with VM---
http://androidforums.com/virgin-mobile-galaxy-s3-all-things-root/774123-carbon-rom.html
(see post # 3)
Disclaimer: Currently looking for the original link for the apn fix and modem, until then, I had them in my cloud account. When I find links, I will change them below.
Apn fix
http://my.pcloud.com/#page=publink&code=jMp
L710 MK5 modem
http://my.pcloud.com/#page=publink&code=eMp
Gapps for 4.3 only
http://my.pcloud.com/#page=publink&code=VTp
Flash installation: with philz recovery do a full wipe afterwards flash rom&gapps Flashing isn't done yet after u did ROM and gapps make sure flash mk5 modern and APN fix then reboot wait 5 to 6mins or less then that and enjoy lte
If u need gapps for old and new here it is give credit to this site from holding them http://www.androidfilehost.com/gapps
I've never had to re-activate phone, but if you do need to, you can just dial ##72786#