How to connect router to modem/router?

Any Virgin Media customers here?

Recently replaced my Belkin router with a Buffalo nFiniti wireless
router and reconfigured the LAN to include a network printer.  There
was a fair bit of work involved and I like the web interface for the
new router so am reluctant to give it up.  In order to upgrade my
cable bandwidth, from 10 to 50 Mbits/sec, Virgin will install a new
combined modem/router, but the bad news from the forums is that I
would not be able to plug in the Buffalo via the uplink port to one of
the LAN ports on the Virgin device.  However, there are hints that it
has been done.  No links to the prescription though.  So does anybody
know if it can be done in principle?

Len