I have done many OTA's for the above carriers without loading any kind of PRL into the phone by using the hanRABet simple NAM programming (generally MDN/MIN/IMSI/SID)most of the time MDN/MIN aren't needed (I use the actual values if known or some non zero nuraber like 0000001234 for MDN/MIN, IMSI =0, and SID set based on home city for the area code .
I then set network selection to home SID only, then do *228xx, where xx (for example PHX) is 00-Alltel, 01-VZW,02-Sprint ,04 Cricket.
I have succesfully activated many phones this way (maybe 75% of those I have tried) to Alltel, Cricket & VZW.
You never have to connect a cable (as long as the SPC is 000000)