The Millenium Hilton, being at the foot of Namsam Mountain, is built on somewhat of a slope, and getting in an out of it on foot (or paw) is a bit of a hike. We found These Instructions on Flyertalk that describe a few alternative routes that avoid some of the climb, so, as a service to our fellow travellers, I thought I'd provide a few photos to help guide you through, as it is, let us say, a little convoluted as routes go, and yes, I fear if you take a wrong turn, you could end up in "The Matrix".
So, this is the door to the Car Park from the hotel on level P6 (accessible from the lift near the Casino entrance within the hotel).