Phone up Microsoft Support.
They will either send 1 of 2 companies to your friends house. Ask them to bring the stickers you will need and make sure he has a suitable box.
If it happens again (which it might), you ring up, ask them to send a 'special box', put the console, and power supply in this time without anything else, and ring up one of the two pick up companies.
You then go to www.xbox.com
, and go to Support. You should be able to link to your account with the details of whats happening.
Both times for me went rather smoothly, and its still working at the minute.