I checked my bindings, adjusted my glasses, and that instant before I stepped into motion, I felt a sensation. That whole time, I felt like I was skiing on a cloud, high above the rest of the world. The privilege, I decided, was not have found this little-known run, but to be gliding across the slopes of a mountain people are praying to. During the dry season, the snow is too hard and icy to ski safely. During the season, the lift only operates on weekends, but it is possible to bribe the caretaker during the week, if he's around.
Emergency services are non existent, so be prepared to deal with any situation.
Bring extra food and water along with your first aid kit. You can rent very poor, but usable equipment at the lodge, and a good idea is to share, as you'll need long breaks between activities. Often busses and tours only go half-way. You also risk being stranded and having to walk the 5 hours back to La Paz. Ask around and get references before booking.