No need to download the vncviewer; just use your Java-enabled web browser.
From http://www.uk.research.att.com/vnc/javavncviewer.html:
Because Java applets can only make connections back to the machine from
which they were served, each of the VNC servers actually incorporates a
small web server. This runs on port 58/xx/, where /xx/ is the display
number, and will only serve the Java applet classes and an HTML page which
contains them.
This means that you should be able to point any Java-capable browser at,
for example:
http://snoopy:5802/
and you should, after a short pause, be able to connect to your VNC
session.
Handy.
--
Kent