Think of a question, then draw sixteen lines made up of random dots. Just like for the Dream Oraculum, you're only interested in whether these lines have an odd or even number of dots. You then translate these into four figures (using lines one to four, five to eight, etc).
From here it becomes even more horrifically complicated, as you then combine each row of these to create a series of "daughter" figures, and then use the "daughters" to create "nephews". You then consult a chart which tells you what it all means.
I can't help but think those twelfth century mystics had far too much time on their hands, and that the original method of drawing lines in the sand was far less complicated.
The Wikipedia article mentions that the term applies to any form of divination that involves interpreting handfuls of sand or stones tossed on the ground. If I'd only read that first I could have saved myself a lot of typing.