There are a host of companies that offer plug spawn including fungi perfecti
The process is prety simple
drill holes
tap in spawn
cover with wax (or not depending on how concerned you are about drying or predation)
Stack, cover/shade, and keep damp while the mycelium goes to work (usually 1-2 years depending on the type of fungi

I have racks of Shitake, Oysters and Maitake I innocluated last spring and they are showing some good activity (I bought 1000 plugs of each and have about 20 logs of the Oystes and Shitake, fewer of the Maitake as I innoculated several stumps first
I am looking forward to soaking them down this summer and getting some mushrooms!!!

Check out Paul Stamets- "Mycelium Running", "The Mushroom Cultivator" and "Growing Gourmet and Medicinal Mushrooms"

Also there are a host of Myco-tribes here with lots of folks with more info and experience