What HGM has referred to as "orthogonal multi-testing" can apparently be found on the web under the title of "Factorial Experiment." An example:
http://en.wikipedia.org/wiki/Factorial_experiment
There are various elaborations of this topic that can be even more efficient. If you follow the links from the above, you can investigate further.
The methodology HGM describes appears to have a solid mathematical basis, but it will be up to you guys to figure out just how well it can be made to work for chess programs.
Factorial Experiment
Moderator: Ras