I've got the same router but with wireless and have been trying the exact same thing. I've posted here and on the netgear forums and it would seem that this router doesn't support bridge (or modem) mode.
I hope i'm wrong but i don't think so. If you find a solution please let me know. The only solution i can see is to keep swapping ADSL accounts which is an absolute pain.
None of the Netgear DG834 Modems support bridge mode, you have to downgrade to a DG 634 for the choice of Bridge mode.
I switch accounts with the click of a button on my Netgear all the time. Mail me if you need help with that