Connecting to a Juniper VNC server from a Mac doesn’t seem to work out of the box. I tried several things before I got it up and running.

I believe the instructions on the following pages finally did the trick:

• http://wiki.oneswarm.org/index.php/OS_X_10.6_Snow_Leopard
• http://forums.macrumors.com/showthread.php?t=775158