Basically what you need to do is have a new location set for the game to install to (Somewhere other than where the game files are currently)
Tell Origin to start downloading.
Pause the download.
Move your files into that location.
Resume the download.
It'll scan that folder, and be like "HOLY *! EVERYTHING IS HERE" and poof, jump to about 98-99% then verify the files.
then you're done. 🙂
