for best success, hunting behind a well known houndsman will be your best bet. They are elusive for sure. They can be called in as well, can't use electronic calls in Colo., hand calls only. I've got 2 buddies that have actually had mtn. lion show up while calling elk during archery season. So they will come to calling.
Compared to deer and elk, I'd say deer/elk are a 3 on a scale of 1-10 for difficulty, and mtn. lion closer to 8 just because they are hard to find. Heck, even with hounds the hunt will not be easy. Hounds might track one down, but then just getting yourself to the treed lion will be a work out.