Just press space for full-screen. and yes I realize pressing space on the N800 isn't as convenient as on the N810. It works though is a bit laggy. and flashes white every once in awhile.

I looked through the source and you just have to change one line to tell it be always be full-screen.
Line 125 of jess.c
conteur.fullscreen = 0;

to

conteur.fullscreen = 1;

and don't forget to read the README:
http://arquier.free.fr/README

And yeah I'm trying to compile it with that above-mentioned line change but I'm having problems with scratchbox.