A few cougars are called and killed every year through out the western states. It can be done for sure. A freind of mine called and killed his mtn. lion two winters ago using a simple rabbit distress. Others prefer to use an Ecaller to get the sound away from them and use mtn. lion sounds on the caller, along with distress. However, Ecallers aren't legal here in CO. for calling mtn. lion.
The hardest part will be getting close enough to a lion to call it. Mtn. lions are widely dispersed, when compared to coyotes for instance, so the success rate of calling a lion is very low, when compared to calling coyotes. To up your odds, get out and scout after every fresh snow, cut a fresh set of tracks and work them. The fresher the snow, the fresher the tracks, the better chance of being close enough to call that lion.