For the new flash tool that will be coming out, will I have to flash a certain iPhone carrier in order to get it onto MetroPCS?

I currently have an iPhone 4 that I flashed with your tool (No sim) and I want to upgrade to the iPhone 4s or 5.

Can you also explain any other things that I would have to do besides flashing it? Such as adding the ESN or any other things to get it fully functioning?