Absolutely no problem at all in a 152, or a PA28.
I've flown there many times in a variety of aircraft including 90hp Jodels and Cubs, and lack of power / size is not an issue.
What is an issue is technique. You need to be taught to use Courchevel properly, or you will most assuredly break your aeroplane and you will not be reimbursed by your insurer.
There are 2 flying clubs active at Courchevel (Aéroclub des 3 Vallées, and Aéroclub du Dauphiné - both have websites, but I don't have the links), and you can do a site check with an instructor that will take you 3 to 5 hours if your general flying is at a good level to start with.
Incidentally, there are 3 landing sites in the Chamonix valley (one for emergency use only, and 2 private airstrips), as well a large number of official glacier landing sites - so your initial question wasn't too far wrong! I wouldn't try any of them in a 152 or a PA28 though!
