Best way is as follows: Get a large de-humidifier. Get a large Wal-mart bin. Make trays inside the bin. Stand the bin on it's end, and scoot it up to the de-humidifier. Duck tape the seals, but leave about a 2" by 12" gap. The shrooms are done when the top of the stem breaks easily in your hand, like a dead twig.
i agree that just letting them sit on sheets of newspaper is perfectly fine. apart from that underneath the layers of newspaper i place a heating cable from reptiles terrarium cage u know just a simple cable device that u plug in to the poers socket and the cable is coated with rubber. it gives some heat not heaps, so it doesn't destroy any compounds like heat lamps and just speeds up the process and perfects the evaporation