Good tips, and it is easier than it sounds in the first place.

- First would be to set up a ssh-server on your Desktop (maybe with cygwin if you are familiar with linux commands) and change the port.

- Second is to forward (route) the changed port, lets say 44422, to the Desktop IP.
Or you just forward port 44422 from the router to port 22 on the Desktop-PC and don't have to change ssh port.

- Then fire up ssh on the n900 and connect to the Desktop with a tunneled port. For this only the ssh start command must be changed, nothing must be changed on the ssh-server.
example: http://www.revsys.com/writings/quick...sh-tunnel.html

- Last step is to connect with tightvnc to the tunneled port at localhost:5800 on the n900. For the tighvnc-server it also looks like you are connected locally. So even if you only accept local (127.0.0.1) connections with tightvnc-server, this will work.