Help rooted and unlocked my sprint gs4 now what?

[androiometer]

Hello! After a couple days of reading I have rooted and unlocked my sprint gs4. I would like to use it with Metro pcs. If I'm not mistaken I also had to down grade the modem to mdc. So now what do I do? I tried to get metro to do it before me but all I got was "they ain't work on metropcs cut we on different towers" so I just bought a blank sim and left.