What setup does he have?
Does have ADSL broadband or cable?
Does he have a USB modem or a router? If he has a router, is it wireless?
If he does have a wireless router then the best way to do it is to connect to the router rather than going through the PC.
If not he can share his internet connection via his PC in an "ad hoc" setup, he would need a wireless device attached to his computer, USB or PCI, and his computer would need to remain switched on.