Sony Ericsson K550i , Unlocking with usb cable?

[wiimii]

hello i have a k550 (black) Locked to T-Mobile and im looking for the easyest option for unlocking , if i have to flash the phone to do it that sounds good but what is the easyest way to do this and what software is the best / easyest to use .

thanks for the help in advance

[wiimii]

ok so im trying to use setool to unlock my phone but theres no option for k550i so which do i choose please