From the TWC forum I like this passage:
"Log into the modem,Go to LAN setup and under Nat section select Bridged. that will grey out all the DHCP
then the Firewall tab and unselect “enabled”

then turn off wireless, save changes, reset it

If any of the above is greyed out call twc"

To reset it, we have to power cycle this one. Now I can plug in my new router from the Arris to the WAN/Internet port of the router and follow the router instructions from there.

I don't see the router model but many require a firmware update before they are stable.

Full rundown at http://forums.timewarnercable.com/t5/Home-Networking/Arris-TG862G-Bridge-Mode/td-p/17939 and do not clone the MAC address.