Unlocking 4.2.1 w/ greenposi0n v.help

[yolifeisGOOD]

so ive successful jailbreak my iphone 3gs with greenposi0n v.rc5_b4, "i know so becuz i got the skull apple icon instead of the regular apple when the phone is being turn on" but i dont know why the "Loader" app to install Cydia not showing up on my iphone. how do i get it on there so i can install Cydia so i can unlock my iphone

Version: 4.2.1 (8C148a)
Firmware: 05.15.05

i read something about upgrading it to ipad 6.15 version and downgrading it? but so confused

can someone run me through the step to get my iphone unlock

 

[yolifeisGOOD]

nevermind, i got my iphone unlock

greenposi0n only jailbreak but cannot unlock
if you want to get your device unlock search for redsn0w to upgrade firmware to ipad then go into Cydia and install ultrasn0w for unlocking

 

[Gregoris]

That is one way to do it, but once you go on the ipad baseband there is no downgrading off it.

you can use this service also, http://www.iphoneforums.net/forum/iphone-4-news-7/iphone-unlock-forever-10737/ but it might not be worth the risk or cash $, i imagine lots of people have tried it by now and there are some good reviews, but whats to stop apple blocking those imeis again?