i want a simple mod (i think)

what i would like is for the background of my lockscreen to change every 5 minutes or so to any of the 288 wallpapers i have on my ipod..

i have tried this which is pretty old:

iPod touch Fans - Outgoing Link

and when i try the timed method it shows merely a blank screen and the random one only shows 1.jpg.

any help is appreciated thankyou