How to flash sprint iphone 4 to boost?

Ok we have an iphone 4 sprint, I think the ESN is clean, we canceled sprint. It's ios verision 6.1.3 with modem firmware 3.0.04. I'm pretty good with iPhones as far as jail breaking goes along with SSH, and even hacking the PRL. But is there a way to flash and how? 10 points for useful knowledge.

Ok yes you can but it is very very hard you have to change the esn and put it to the boost mobile network but before that there's a lot over riding it and putting new firm ware and.much more the reason I'm not saying how is because it's illegal right now only boost.mobile can.directly but they decide whether it's eligible but… If you smart enough to hack it why not. Look it up and find the steps I found them before when I was hoping to do the same but with a iPhone 5 and it's hard. So up to you