When you arrive at the posted coordinates you will see a sculpture. Count the total number of steps (the ground doesn't count but the top does). Make sure you count them all.
Call this number "A". Plug A into the following equations, and plug the answers of the equations into the partial coordinates below. Those coordinates will take you to the final stage. I had trouble getting consistent readings at the final, so use your geosenses when you get close.
Muggles, muggles, muggles. Please be watchful. Follow the instructions on the container.
XXX = A times 53 plus 6
YYY = A times 82 plus 4
N 40 46.XXX W 096 40.YYY
Special thanks to CU.
You can check your answers for this puzzle on GeoChecker.com.