As this is a very old thread. I will just post for those who are searching for the Challis Cemetery and cannot find an address or any directions!
The address is roughly
625 7th St, Challis, ID 83226
GPS Coords: 44.501054, -114.231902
It's very easy to find! Get off at Main St and go south on 7th street for a few blocks. Can't miss it!
Google maps has a satellite image of it with images from 2008.