I can give you a basic rundown of what to do as i have both the router and itouch 2G with 3.0 firmware. One thing you might want to include before hand is if you have a encryption on your wireless network(a password) and also if your SSID is visible or hidden.
If you have no password simply go to settings on the itouch, tap the wifi button, make sure it says wifi ON and choose your network by the name in the list. If you have a password follow the same steps but it will ask you to type in your password when you click on the network. If your SSID is hidden you must hit 'Other' and manually type in your SSID, choose your encryption and then type in your password.
Also you can manually type in the IP address, subnet, gateway, etc for the ipod if you hit the little blue arrow next to the networks name in the list.
Like i said this is a basic rundown and without knowing if you have any other advanced settings on your router this is as much as i can help.