I'm assuming you have an ADSL wireless router attached to the phone line and you want to set that up with a laptop that will only access the Internet by WiFi.
You really need to set up the ADSL Router part through a LAN cable attached to the laptops LAN socket. After you've set up the basics you can also enable WiFi but using the LAN connection.
Then use a USB 802.11g dongle on the laptop to access the Wireless Router and the Internet.
But I think you will have to go through the hybrid LAN route initially.