Probably a stupid question about flashing to MetroPCS

[habbywall]

Alright, I rooted my evo using the htcDEV method.

Now, how do I flash it to MetroPCS? If I just download MetroDroid, put it on my SD card and flash it is that all I need? I've found a couple guides to flashing to MetroPCS and they say things like these ROM's are only for people that are flashed to Metro so I'm just wondering if I'm missing something easy?

Thanks for the help in advance.