Look it up on Youtube, I can fill this page explaining it, but you have to see it. It's easy enough but make sure Boost will activate it. It typically takes a good amount of calls to get a Sprint phone activated. Also Sprint locks their phones, you need to get the MSL so you can enter the phones programming menu. SOMETIMES Boost will call Sprint and get it, but that is VERY rare. Plus if the phone in under contract, on an acct, or has money due they won't activate it no matter what.
MSL is the CDMA Subsidy lock code. You must enter it each time you go into manual programming. It's not a one time thing like GSM phones.