Here is the cast of characters:
1. blopr: A server that is behind a company firewall that I want to view its vnc session
2. netnet: A server that is on the internet that I have access to.
3. Me: The humble system admin who wants to view the VNC session on blopr.
Here is how I do it:
on Blopr:
vncserver :99 -depth 24 # and whatever other arguments you want to have.
ssh -R 5999:localhost:5999 root@netnet.example.com
On NetNet:
redir --lport=5989 --cport=5999 --caddr=127.0.0.1
On yours-truleys humble macbook pro:
vncviewer netnet.example.com:89 # enter the password for blopr's vnc session
Presto! You are in there my friend!
Bonus for you to try: Suppose only SSH is allowed out from blopr? This is left as an exercise to the reader. But the trick is its very similar.