3g 8gb itouch updated to iOs 4 wallpaper lock screen?

So I recently updated my itouch to the iOs 4, not knowing it only worked for the other gens. I don't mind it, but I was wondering if there was a way to change the wallpaper of the lock screen? I managed to fluke it a couple of minutes ago, but I did something and I can't get it back.
Oh yeah, it doesn't say set as lockscreen, when I go to the picture, it just says " set "