How do I update the Sprint PRL from Cyanogenmod?

I just flashed my Galaxy S4 with Cyanogenmod. I'd like to now update the Sprint PRL. How do I go about doing this from Cyanogenmod? Do I have to download a new copy of the default Sprint firmware to update the PRL? And, if so, what is the easiest way to do this?

This is a list of Samsung S4 stock ROMs, but I am in the SPR or XAS zones? What does that even mean?

Is there a shortcut to backing the entire phone up and running the ROM? Is there a way I can boot into the room without flashing the phone, just to update the PRL? Is there an easy macro for all this stuff, or can it be simply done with an Cyanogenmod hack?

Currently, my Sprint phone is on PRL version 1.