Question abt setting up cable modem w/telco return

[larry@kryten.dt.navy.mil (Larry Kelly)]

Not sure if this is appropriate place, but here goes:

   Would someone have an idea as to how to configure debian to handle a cable 
modem connection where the return is via serial modem (telco return)?  I 
figured that I would setup a ppp link as the default route, and also have an 
ethernet adapter configured for the incoming data.  Here's part of the 
problem.  Is it possible to have ip masq operating in such a configuration?  I 
would tend to think that ip masq won't work, as the dynamic port creation 
would present a problem with multiple tcp streams.  

   Anyone have any other ideas??  (Like maybe some config params??  :)


   Thanks!
    -larry