Can't recommend any tutorials. But you shoot the character on a green screen, give them a frame, the same size as the TV to crawl through, and have it at the exact same placement the real tv in the scene would be at. Then shoot the scene with a green screen paper taped to the TV screen. You'll have to remember high your camera is and at what angle to the TV. You'll have to do your best to duplicate the camera setup. Best case situation would be to place your camera, film the tv area. Leave camera,alone in same spot. Remove TV, and put green screen with picture frame for actor to crawl though. That way all your setups match.
Key out your actor, and composite him into a background that matches what you're going for on the TV. Giving that footage a look, that is diffefernt from the room environment that the tv is in. Key out the picture area of the tv, and put your footage of him crawling out. As he crawls out of the TV, duplicate the footage, create a mask, so as each part of their body passes that TV plane, its color corrected to match the room environment, like he's entering the real world. Like if he's black and white on the TV, but becomes full color once past the plane, in the real world.
Does that make any sense? Would take a little planning, but I think could all be done in After Effects.