If you need to change the proxy settings for the any of the system account like Network Service you can use the “bitsAdmin” command as shown in the following example:

bitsAdmin /Util /SetIEProxy NETWORKSERVICE MANUAL_PROXY [myProxy]:[myPort]

You can find the complete reference for this command at: http://msdn2.microsoft.com/en-US/library/aa362813.aspx

Thanks,

Lito