Well,
the problem is that most VNC servers are built to support the X Window System, rather than the window server we have in Mac OS X.
I'm not at my mac at the moment, but you should try this:
Log out of the GUI.
Shell into the computer.
Try and manually launch the VNC server from the shell - probably as root.
All at your own risk, of course. My guess is the LoginWindow will prevent other apps from launching, so maybe try modifying the files listed at this link:
http://www.opendarwin.org/en/faq/ch02.html#loginwindow
so that they load more than one thing up.