All this script will do is chmod the download directorys of the iTunes software updates. When it tries to download it will be denied permission. Quite simple.
#!/bin/bash clear echo "This script will chmod the download locations for Firmware Files, So iTunes can not download firmware." echo "AKA it will prevent iTunes from auto updating your device." echo "" echo "" echo "To restore firmware just hold down option and manually select the firmware file." echo "" clear echo "Made By: Wesley K" echo "http://wesleyk.me" echo "http://wesleyk.me/twitter" sleep 2 read -sn 1 -p "Press any key to continue..." clear echo "Now I need your password to continue" echo "Killing iTunes now" sudo -v sudo killall -9 iTunes sleep 2 clear echo "Im going to make all the folder needed to future proof a few things" echo "If errors occur here, No big deals." sudo mkdir ~/Library/iTunes/iPad Software Updates/ sudo mkdir ~/Library/iTunes/iPod Software Updates/ sudo mkdir ~/Library/iTunes/iPhone Software Updates/ sleep 2 clear echo "I am going to dump all the current files in your update folders." echo "This will prevent any updates from downloaded firmware." sudo rm -rf ~/Library/iTunes/iPad Software Updates/* sudo rm -rf ~/Library/iTunes/iPhone Software Updates/* sudo rm -rf ~/Library/iTunes/iPod Software Updates/* sleep 2 clear echo "Now preventing iTunes from downloading new firmwares." sudo chmod 444 ~/Library/iTunes/iPad Software Updates sudo chmod 444 ~/Library/iTunes/iPod Software Updates sudo chmod 444 ~/Library/iTunes/iPhone Software Updates sleep 2 clear echo "Made By Wesley K" echo "Give me credit if you use it" echo "For safe measures I would run this script after iTunes updates, It shouldn't affect it but I don't know yet."
[crarko adds: I haven't tested this one. As I've mentioned before, I don't jailbreak. If you download the script it has a ruby (.rb) extension. It's not ruby so change it to .sh. Note that you could also just go chmod 444 the relevant directories by hand in Terminal. The original permissions on the directories is 755 if you wanted to change them back.]

