Accessing DOCSIS diagnostics from within/behind FreeBSD router

[J. Seth Henry]

Guys,
I'm not sure if this is even a FreeBSD question, but googling hasn't turned up 
much on it, so I thought I'd toss this one out there.

I have a Motorola SB5100 cable modem directly attached to a FreeBSD router 
(running ipfilters/ipnat). The external network is a comcast segment, and is 
assigned a dynamic IP. The internal network is routed on 192.168.1.x, where 
the router is 192.168.1.254.

The trick is, the cable modem is on the "external" side, but apparently 
listening on 192.168.1.100 for HTTP requests (for its diagnostics report).

Is there anyway to access this diagnostic page without temporarily plugging 
the CM into a Windows box?

Thanks,
Seth Henry