Sov has it right. As long as someone is selling sojs on the same server on b.net, the Diablo Clone will spawn in every Hell game on that server. I have tested the method I have posted several times, and it is now confirmed. The thresholds for the soj counter (or random spawn % calculations) is the only mystery now, and only battle.net staff would know about that.

It works, and it is correct. Unless a battle.net admin was to come in and say differently, I wouldn't even waste time wondering if this was wrong.