Coming from I-5, take the downtown Eugene exit and then look for signs that will take you to the University of Oregon (which is on Franklin Blvd., on the Eugene side). Keep on Franklin, go past the U of O, and just before you reach Glenwood, take the first light on the right. That is Glenwood Blvd., and you go about a mile until you see Judkins Rd. on the right. Take that road a couple of blocks up the hill. Park by the iron gate and you can enter on the left side of it.
I don't know about a plot map. Where you park you will see a contact phone number on a sign that you might call.