how to change the resolution to 960*640?

at this document:<>
(http://www.cocos2d-iphone.org/wiki/doku.php/prog_guide:how_to_develop_retinadisplay_games_in_cocos2d?s[]=retina)

Device Points Pixels
iPhone4 in HighRes mode [2] 480×320 960×640

I want to change some codes,In order to make

Device Points Pixels
iPhone4 in HighRes mode [2] 960×640 960×640

how to change?