Vista - Two-Way Xml Binding?

Is it possible to do two-way binding with an XML data source? Notably, I
have a couple of window-wide doubles that I would like to animate, and
then have a whole bunch of controls bind various properties to them, so
that the one animation runs all the controls.

I would *like* to do it with my XML island, but any other way would be
perfectly acceptable (although I'd prefer to not create a special class
just for this).

Thanks,
Nick