well I think this would actually have to be a feature for Messenger itself, unless a proxy is used.
I can only think of two ways of making this happen:
- Use a proxy and send the protocol command for adding the new contact.
- Use SendMessage, FindWindow etc to bring up the add contact window and paste in the address and click next etc, but this would obviously be visible to the user.
Both ways would work, but the first way seems a bit bloated using a proxy just for one function, maybe its something Messenger Discovery could add as it's already using a proxy?
The second way would work, without a proxy but as I said it would show the windows and wouldn't be much quicker than manaully adding the contact.
/ 
