[Help]Setting up a VPN for Call of Duty Modding

Hi,

I want to set up a VPN, Like Hamachi to connect me and my friend via System Link to play with Mods, However I dont want to have an active connection to xbox live.

For example:
At Home I can System Link with my brother, Just by removing the DSL Cable from my Router. However for the Hamachi or other method to work I will need to contact to my friend via the internet. What I am asking is there anyway to stop Xbox Live from connecting to the servers whilst keeping a connection to the internet and my friend.

Thanks,
Storm.