SMCD3G-CCR in Pure Bridge Mode

I need to put my SMCD3G-CCR cable modem in pure bridge mode.  I called support twice and was told that they can only put the modem in passthrough mode (which it was already set to).  However, postings on this forum says otherwise.

Is there something I can do to get this done ASAP so that I can VPN into my work come Monday, July 7, 2014?

Thank you.