How 2 replace Game Files with HQ versions I resize myself??

I can't figure this out , I had been trying to convert my game to HQ size and found a ton of files that would replace the default game textures in to the appropriate size, however it for whatever reason , didn't work on the default skin and a couple of the outfits that were added after the game updated with holiday packs and so forth. I have no problem resizing the textures myself, but I honestly have no idea where I would access the files and how I would make it work? Its something so specific I can't find a tutorial for it. 

I also like the idea of replacing the actual meshes in the future in case I ever decide to make the game a straight up time period and I don't want automatic sim fashion to interfere. Not really a priority just an added bonus if you know anything. 

Im grateful for any help that might be given.