OK, problem solved. Found the following in the CM7 for RK2818 topic on xda-devs :
Originally Posted by fun_
and here is another way to install update.img on tablet w/o button.
put update.img into root of SD card, then run following command on root shell (or gscript)
mkdir -p /cache/recovery
echo ...

Would it be possible to copy/install the original Arnova firmware update tool on Cyanogenmod so I can flash it that way? Or would that be too tied in to the system?

There's a lot I like about this rom, look and feel and tweakability are great but I'm having problems with GMail. Each time I open an email, it starts to open then "crashes" back to inbox. I've tried clearing cache, removing and reinstalling but no luck. Also, the browser crashes frequently.
Is it ...

I flashed my Arnova 10 with CM7 using the standard procedure from sd-card (archos/arnova ui).
Now I want back since CM is just not quite stable but I find that my USB port isn't working! So no RKBatchUpgrade etc :evil:
Recovery mode isn't an option either since I don't have the touch enabled ...