SOI - Automated Activation with Proxy

I need a solution to automatically activate our desktops right after SOI.

I have seen solutions where you use to set the proxy information.  Does this need to run as a user on the system or can this run as the system credentials (symantec management agent creds)

1. netsh Winhttp set proxy x.x.x.x:port

2. slmgr.vbs /ato

Then after doing this what is the command to remove the netsh command I just applied to the system?