There is a test implementation of the SVG protocol for the whiteboard. It is still in its infancy and will get a major rewrite when my tkpath package will be used for all whiteboard graphics. So stay tuned.
First, you need to be able to run from sources. Secondly, you need to specify some command line arguments. On unix you just do
./Coccinella.tcl -jprefs_useSVGT 1 -prefs_trptMethod sipub
but on Windows and Mac you first start the Wish program, then in the console window write
set argv "-jprefs_useSVGT 1 -prefs_trptMethod sipub"
and then File/Source and pick Coccinella.tcl.
It is possible that this also works for the binaries if you start then from a shell (DOS on Windows).
Images are now transported using the so called sipub protocol which just plugs into the standard xmpp way of transporting files, which have the ability to penetrate NATs and firewalls if the server has a bytestreams proxy service. Actually, a barrier on one side is handled without any additional proxy server support.