I was able to do this by adding the debian repos to /etc/apt/sources.list and installed
apt-get install xorg
apt-get install gnome
after the system came up I brought up synaptic and looked for 32-bit, and installed the 32-bit compat libs for GTK. Then I did a manual install of Firefox 3 by copying it to /opt and also a manual install of java by copying it to /opt. symbolically linking the java executable from /usr/bin and also symlinking the libjavaplugin_oji.so in the /opt/java/plugin/i386/ns7/ to the same name /opt/firefox/plugins/directory.
However, after too many apt-get updates and upgrades I destabilized the system, probably due to conflicting packages, so I think proxmox needs to have these in its own repo. You're gonna have to repackage 32-bit firefox and sun java and probably also flash.