True Bridge Mode

Hello, I've been trying to place my modem into true bridge mode and handoff all functions to my router I've called the support number several times and tier 2 support even contacted with me with no success. Starting to get frustrated with this issue, I do not have a staic IP I'm trying to accomplish exactly what is posted here in this thread http://forums.businesshelp.comcast.com/t5/Equipment-Modems-Gateways/Need-my-Modem-in-True-Bridge-mode/td-p/12622

Thank you