All you do is copy the snippet of text and paste it. Be sure to backup the iTunesPrefs.xml file and kill iTunes before starting. The instructions are as followed:
1. Locate your iTunesPrefs.xml file. It’s usually located in C:\Documents and Settings\username\Application Data\Apple Computer\iTunes or C:\Documents and Settings\username\Local Settings\Application Data\Apple Computer\iTunes.
Hint: If the folder Application Data does not show up, make sure that hidden files are visible in the Windows Explorer
2.Backup your iTunesPrefs.xml file
3.Open iTunesPrefs.xml using a Notepad
4.Search for a section called User Preferences and paste the following snipped into the User Preferences Section after the first <dict>:
<key>DeviceBackupsDisabled</key>
<data>
dHJ1ZQ==
</data>
5.Save the file and restart iTunes. Backups should now be disabled. To enable backups again delete the XML Snippet from iTunesPrefs.xml file.
When you’re done, it should look like this:
I’ve tested it myself and can say that it works. Thanks iphonefreakz