Unfortunately after doing a search for you, the only way to update your explorer to 4.0 Ice Cream Sandwich would be to root your device.
If your interested in rooting, follow this link to the guide:
http://forum.xda-developers.com/showthread.php?t=1415223
Make sure you read it numerous times before proceeding forth until you understand what your doing.
If your unfamiliar what being "rooted" is, follow this link and read up about it:
http://androidforums.com/showthread.php?t=443432
DS