You should not attempt to reach this cache from Interstate-15. Take Exit 64, and then head up 93, until you get to the entrance to the truck stop on your left. Don't turn in there - Instead, turn right, and follow the big loop around and you will end up on Las Vegas Boulevard North.
There's not much room to pull off of the pavement, but I guess you'll figure it out. The hide location is about 600 feet or so out in to the desert.
Look for the yucca (You can't miss it!).
There is a 1972 Eisenhower Silver Dollar for the "First To Find".