Follow this link to get a map of Carnegie with names of trails:
So you'll be at Tyson's Basin by the maintenance yard? In the parking lot there, or more at the entrance?
I'm not coming, but just trying to help make it more clear. That parking lot is where I used to start when my son was first learning to ride. He came very close to landing an RM-125 on the hood of the only nice car parked there.
We later parked just west of Skip's, which now has some other name.