Estava com o mesmo problema, encontrei a solução nestes sites, espero que ajude !!!
http://www.iphoneheat.com/2009/04/how-to-customize-your-iphone-with-winterboard-step-by-step-guide/
http://www.youtube.com/watch?v=0Q9WPlLTGyg
http://applerevcenter.wordpress.com/2010/08/21/tutorial-como-usar-o-winterboard/


