simulation that I've done was more like PoC and it is currently not enahnced any more (mainly due to lack of time) and it was not yet prepared for jBPM5 at the point I worked on it. Unfortunately there is no formal documentation for it. There is an initiative for simulation for both drools and jbpm you can find it here
Would be good if you could express your needs and requirements for simulation so we could take them under consideration as well.
Cheers