explorer connection to remote desktop

Not sure the best place to post so I'll start here.

I have a computer running XP and it is configured to enable windows remote
desktop. It works. From a remote system using a differet ISP I connect with:

MYIP:MYPORT/tsweb


One client uses an ISP that blocks outgoing (yes, thst's right, outgoing)
ports
to this host. The ISP knows about this but can't recommend solutions (too
complicated).

I can reach a webpage served by the host computer (MYIP:MYPORT/default.htm)
from this client if I use http-tunnel. But I cannot make the tsweb connection
(connection refused).

Has anyone done this? Could you give me a stepwise procedure?