How to pass geometry to gdmflexiserver?

[Romeyn Prescott]

I recently installed the Xnest package which adds a rather cool 
option to the Applications-->System Tools menu: New Login in a Nested 
Window.

I can run this (gdmflexiserver -n) from my Mac running Apple's X11 
when I 'ssh -X' into this box.  It gives me the GDM login in a handy 
window.

Does anyone know how I can pass geometry parameters to this command? 
I end up with an 800x600 window, and I'd like a larger one.

Thanks,
...ROMeyn
-- 
signat-url: http://www2.potsdam.edu/prescor/signat-url.htm