To be honest, this would be absolutely amazing, although I think adding Assassin's Creed style climbing might ruin the game's style a bit. Vaulting over objects and peksy terrain, I'm all for, and I think it should be pretty simple. All you need to do is setup the scripting for it and the animations. I think the animations part would be the easiest. Speaking from personal animation experience, although not with the same game, all you'd need is several hours and the actual will to do it. After you've passed those, it's easy. Once the scripting is done, set the two up, and boom! You've got yourself a little trinket that makes your character look less stupid :P