m0n0 and TiVo multi-room viewing over vpn

Both my parents and I have TiVo and a cable modem.  I have a m0n0wall
at my house, and will be installing one in there house soon to create
a VPN between us.

I'm trying to get TiVo multi-room viewing working between us, so we
can share shows.  I realize if I got it to work, it would be quite
slow, and that is not a problem.

The problem is this, both TiVo's need to be on the same subnet and be
able to recieve each others UDP traffic to identify they are available
to each other.  Is there a way to do this with m0nowall?

A few thoughts of how to do this would be to create a PPTP VPN between
us.  Will PPTP pass UDP traffic?  Is it possible to create a PPTP VPN
between us, withought forcing all of their traffic through my house?

Is it possible to do this with an IPSEC VPN?  

Any other ideas on how to do with with a m0n0wall?  

Thank you.  

Joe