[Q] Need PRL/Profile Update: AOSP 4.4.4 topic

Guys, I've been all over the site the past couple days reading posts and I haven't figured out if what I'm trying to do is possible I just flashed my first custom ROM - Gummy - KitKat 4.4.4 on my GS3 Virgin Mobile. All is fine but I have very weak cell reception - 1 bar most the time. I saw on some posts that it's hard or impossible to update PRL/Profile on AOSP ROMs. Which is it? Do I really have to flash back to stock and update then flash back to custom ROM? Is there a way to fix this issue without doing all of that?