Well for fun I had a quick play and here it is. Looks pretty ugly actually, but all I did was simply invert the palette. i.e. black and full brightness are exchanged and the two intermediate levels are exchanged. Playing with palette settings might produce a better result but I doubt it.

Patch this against 2.0b11 (will probably patch against most kernels OK)
http://www.uq.net.au/~zzchack/files/displayinvert.patch

or Hijack v200 + Display invert binary for a Mk2/Mk2A
http://www.uq.net.au/~zzchack/files/v200.hijack.v200b11.displayinvert.zImage