I am using a Vonets VAP-11g Wireless bridge and that is working great for over a year.
You need a web browser to set it up (I used the laptop - not sure an Ami browser will work).
Once you set up the wireless connection, you can plug it into the Ethernet port and it will transparently send the Ethernet packets over WiFi.
You can buy a separate power adapter to supply power but what I did since I have a towered A1200 was to cannibalise a USB female end and solder the positive and negative 5v from the PSU to the USB connector outer pins and screwed it inside the back of the case and plugged the Vonets USB lead into that. It supplies the 5v needed to run the adapter.
You can get these very cheaply - maybe ten dollars/pounds new.
