[Hampshire] Reverse Tunnel and NX

I have set up a reverse ssh tunnel from a machine behind a firewall
which allows no inbound traffic. This is great - I can now ssh to
localhost on the machine where the tunnel terminates, and get onto the
box. However, I want to use NX, and the machine where the tunnel
terminates isn't my workstation - it's just a machine with a shell
account. I wasn't thinking straight, obviously - as if I were on that
machine, and that machine had X and nxclient, I could connect to
localhost. What I want to do is be able to point nxclient on my
laptop at the machine where the tunnel terminates, using nxclient, and
get on the box.

Like this:

[workstation] --- ssh -R 2048:10.0.0.50:22 stephen@???
---[site firewall]---[my firewall]---> [morris (10.0.0.50)]
<---nxclient 10.0.0.52 -p 2048--- [laptop]

My apologies for emailing first, before some serious googling - but I
won't be near a computer for the rest of the day, and really need an
idea of where to go next by tomorrow morning. My hope is there's
something simple I can do to allow "morris" to listen on the port that
appears as the result of the ssh tunnel. Iptables translation
perhaps? But is there something even easier?

S.