Well, it's not exactly "instantly". It does take a little bit of time.
Tired of finding the right CC and downloading them to your game? Don't have access to the right CC because the site is down and all you have is a picture from someone's game?
Well, try this: download your favorite lots loaded with CC. Chances are, the lots will be all packed with period objects, walls, floors, and terrains. If you don't have the right expansion packs/stuff packs to install the lots, then do not fret! You can just install the lots with sims2pack clean installer. The CC installed in your game will be properly named as the original name, so it's not going to have squiggly gibberish or anything of the sort. If you want to have some clothes, then All-About-Style and Parsimonious are the best places to go to find period custom content.
I tried this method recently, and I absolutely love it! There are a few meshes that aren't included and some objects flash blue in the game, but as far as I can tell, most meshes actually are included in the game so you can play the CC instantly!