SixTrak 6-Output Modification?

[Fitzhugh, Karl]

Anyone have any details on the 6-output modification for a SCI SixTrak?
I've seen mention of it on this list, and elsewhere on the net, but
can't seem to find any actual details on it. Basically I'm looking for
plain and simple instructions on how to do it - I'm not exactly an
expert at this sort of thing!
Hope someone can help, or point me in the right direction - thanks in
advance.
Karl