1. Upload the icon you want to use to a webhost (imgur.com is good) (3GS *must* be 60x60 px)
2. If you haven't already, Create the shortcut on your iphone springboard.
3. SSH or iFile into /private/var/mobile/Library/WebClips
4. You will need to find the directory for the newly created webclip, it'll be a long string of gibberish but the .plist in each folder should let you know which one you're dealing with.
5. Edit the info.plist to reflect :
Code:
<key>IconURL</key>
<string>http://yourhost.com/iconname.png</string>
6. Copy the same icon you uploaded to the webhost into the directory calling it Icon.png (w/ capital I)
7. Here's the vital part - set chmod 0444 on info.plist and chmod 0555 on the actual 'gibberish' directory (this prevents it being overwritten by the original icon again)
8. Go back and click on the springboard icon to reload the new icon & respring - the icon should now be permanantly changed to your version.