Sure it can be done.
Directly...not a chance. Just get a job for an operator that works in the mountains, learn how to fly in the mountains and learn how to use a long line. After 3-4 years you could be good to go.
A big part of flying in the mountains is performance. How many times in your career in the North Sea have you had to actually had to consider if your helicopter would have the power to complete the maneuver you are asking it to do?
Seriously....say you lift off a platform with 20 guys on board...how often is it where would be in the position to fly to another platform 2 miles away and not have anywhere near enough power to land? In the mountains performance of the helicopter changes huge amounts depending on where you are. Sometimes literally moving a few hundred meters can change a power requirement from 50% torque to well over 100% torque with the same load. When the power is not available it can get real ugly real fast. Now do this with 2 guys hanging under your helicopter, or more accurately know when NOT to do it. (Dramatic examples....it’s easy once you know what to expect!)
It’s all what we are comfortable with I suppose...put your average VFR mountain guy in a multi crew off shore environment and we would be totally lost!