From Evanston, Wyoming head South on Hwy. 150 (Mirror Lake Highway). This will be exit #5 if you are coming into Evanston on I-80. Follow the Mirror Lake Highway south until the road is closed for the winter. Just before where the road stops there is a large parking area on the left side of the road. You'll need to pay a few bucks to park here (forest service). From this parking area the trail system heads out to the South (from the northeast corner of the parking area). Refer to the map that you get from BRORA with your permit for details on how to get to the yurts from the trailhead.
If you're going in the summer when the highway is open you'll know when you get to the parking area by taking your first left (about 1/4 mile) after the Bear River Lodge. I didn't measure exactly how far this is from Evanston, but it's about 20-30 miles.