i never knew how ppl did it to be honest but you can change that to anything you want the slide to unlock and the wifi name and the carrier name, everything. a quick google search will tell us though. ppl have been doing that since 1.1.4 firmware though
[ame]http://www.youtube.com/watch?v=_NzTyVz-KCs[/ame] . mute the video ( lame music )