I actually don't understand your question fully. You want to repurpose your game controller to control your TV? Are you intending to open the controller and hot wire it? Or do you want to make a man in the middle type box that intercepts signals from the controller and blasts the appropriate IR codes to the TV? Is the game console controller supposed to function like before while having this new capability? What type of controller is it?
As far as learning curve for something like this, it depends, some people pick it up fairly quickly and for others it might take some time to learn the fundamentals. Depends on your background. Knowing programming can give you a leg up, or knowing basic electronics. But since there seem to be a decent number of libraries and modules already available it may not be too bad.
It's hard to tell because we don't know if the existing libraries already handle the IR protocol you're trying to reverse engineer. Also if you get stuck you might need an Oscilloscope and a Logic Analyser to inspect your signals. There are learning curves to all of this. And you might have to invest into some test equipment and tools.
It's definitely beyond the scope of a first project I would say. But you might get lucky.
Good thing is, it's cheap to try it out. Arduino clones can be had for a less than $10.. and the modules are just as cheap. Get an Arduino, get your feet wet, make a few simple Arduino projects, LED blinker and so on and then see if you have what it takes to try out the IR stuff.
Dave did a video on IR reverse engeneeiring while back, so here is a little taste of what might be required: