It is usually possible to rip models from games on the Steam platform, although some games and ripping software are not always compatible. Short answer, it can likely be done, but it requires (besides the game software) also ripping software, followed my conversion software for the files, and often specific scripts in the modeling software. There are several tutorials on youtube as well, but you're not going to find a one-stop tutorial that will be guaranteed to work. YOu might be able to find someone to get them for you, but not likely for free.
123d catch doesn't usually play nice with screencaps, in my experience. You end up with a mess that is waayyy more work than it's worth to try and make usable.
Also, I haven't really seen too many eyebrows raised over people extracting models from game platforms; I think studios would be more concerned with what you do with them after you've extracted (i.e. try and sell the models on Ebay lol, etc...) Most extracted game models (the Pacific Rim Jeagers are a great example) are nowhere close to being immediately usable in other formats anyways, and will require hours of 3d modeling to get them to a usable state (as a costume or even just a static model).