If its a 3G then no SHSH's are required. Also make sure you have the correct firmware file for your device. The 3GS firmware file wont work for the 3G. The link below is for 4.0.1 for a 3G (not 3GS)
iPhone1,2_4.0.1_8A306_Restore.ipsw
P.S. I understand your friend has his reasons to upgrade but I agree completely with unleashed on staying away from iOS 4 on a 3G...
Yes, that is the exact FW I downloaded to my Mac. Does it matter if the phone has to be off before starting DFU?
I don't understand why I'm getting that message...