High Contrast Black GPO or Registry

[dyson38]

I have a few pupils that are visually impaired, I have them in a seperate OU (server 2003) and wanted to change their desktops (XP Pro) to the colour scheme High Contrast Black option in Display settings.
After some extensive searching it appears this cannot be done via Group Policy so I thought well maybe a registry hack that applies when a particular user logs in and reverts back when they log off (im yet to find one that works).

Anyone have any ideas as to what may be the best way to do this without me walking round to 100 machines and configuring them seperately?

[mrbios]

try the key combo: shift+alt+print screen when logged in as a kid, kids can then do it themselves, a bit annoying when others catch on though and leave the PCs on that screen

[p858snake]

Find the registry keys for setting it and disabling it and then script it and set them as log on and log off scripts possibly.

Heres a script for disabling it on login so thats partly the way there: Disable Sticky Keys and High Contrast

[dyson38]

Unfortunately the ctrl:shiftrint option is out of the question, some of these kids are only 5 years old, this need to be totally automated when the user logs in and logs out.
As for the registry hack, I found this one before i.e. switch high contrast on or off but changing the settings Ive had no luck with.