I have the game installed on two computers at home setup on a local network, so I simply copy/pasted the files, took about 10-15 minutes. Although, I also had to install the initial client downloader file that contains the .dlls and etc before the copy/paste worked, and then launched the client from the copied Square Enix folder.
I'm sure copying the SE folder and burning it to a DVD would work just as well, I didn't take the time to look at the file size, but at most, you might need 2 DVDs. Just burn the SE folder onto it as data, just the way you would a flash drive. Once again, you're probably going to need to add the initial setup file in there as well, so that his computer will register the .dlls, .exe, and etc.