I can only find "work arounds" and ""SSHFS" solutions, neither sound desirable..
2 commercial programs exist, 1 is for Mac, and the other is for Windows/Mac.
http://www.wideanglesoftware.com/touchcopy/
http://www.ecamm.com/mac/megaphone/
Both programs manage to "prod" the Apple ITouch/Iphone into disk mode, but they don't document the method.
I suppose if someone used a USB bus sniffer they could determine what extra magic is required to enable the feature, but I don't own a Windows system or a Mac.
Nothing more I can do.. my sincere apologies.