Are you sure it's SSH, if you're using port 23?
The easiest way to be able to do this is to use SSH's built-in port forwarding. The syntax is -L localport:remotehost:remoteport. So for instance, if you use this command:
ssh -L 5902:localhost:5900 email@example.com
you will be able to connect on port 5902 on localhost which will then be tunneled to your home PC's port 5900. In this case, the ``localhost'' in ``5902:localhost:5900'' refers to the fact that it's connecting to the machine you've SSH'd into.
To connect to your home computer's VNC server, all you must do is fire up your VNC client and connect to localhost:2 [or just :2] since 5902 is VNC display number 2.
Let me know if you have any more trouble.