I managed to get my NF4V working in bridge mode. It’s not super intuitive unfortunately.

First you need to find your PPPoE username and password. The username is your usual Orcon one, but the password is random and set in the modem automatically. The easiest way to get the password is to 'unmask' it from the password field of the NF4V using the firebug addon for firefox. Here's a short video that demonstrates the technique http://www.youtube.com/watch?v=HVkXav70UvU

After you have the password you can put the modem into bridge mode. To do that you actually have to delete the PPPoE WAN interface and then create a new WAN interface, choosing "bridged" rather than PPPoE. When you create the interface it gives you the option of using the PTM or ATM connections, choose PTM. Once that’s done you can plug the WAN port of your router into the LAN1 port of the NF4V and set up the PPPoE connection using the credentials found in the first step.

If it all goes horribly wrong you can start again using the factory reset button.