If your friend has NO ADSL, then your only possibility is dial-up! Or you could buy a 3G card (if in an enabled area).
If your friend has already got ADSL, but no means of sharing the connection (i.e. his computer is linked directly to the ADSL modem), then you have 2 choices.
One is to bring a hub or router in between the ADSL modem and his computer and share the connection (either wired or wireless), assuming that the existing equipment can support this (e.g. not a USB-only connection).
Or you could plug YOUR computer into his ADSL modem and run through the setup routine to HIS ISP.
A variation on the first would be to leave the existing computer connected to the ADSL modem, with an additional hub / switch connection to provide a separate network for ICS (Internet Connection Sharing). This is one way around the USB ADSL connection.
SD