Linksys VPN router behind a Verizon FIOS wireless router?

I have a client who recently had FIOS installed at their small office.  I need to connect their Linksys VPN router up ot the internet, and it seems I have to install it behind the Verizon provided wireless router/switch.  I've talked to Verizon and they said that all I need to do is turn off  LAN DHCP on their router and install my router.  On my router change the internal IP address to something different then the internal ip address of their router.  I assigned the outside ip address information to my router that was assigned to their router as well.  After doing this Verizon claims that their router will automatically act as a repeater and stop acting as a router.  I am unable to get this to work.  The Verizon router will not pass traffic from the Linksys router to the outside world.  I can plug my laptop into the Verizon router and it will pass traffic, but from the Linksys.  I asked Verizon if they could tell me which router it was seeing on the outside based upon the MAC address, they claimed that they could not perform that kind of test.  So my guess, is that the Verizon router is not acting as repeater but a router and my router is not being allowed to work.  Does anyone have any suggestions?