So, the only game I have ever bought a physical copy of that needed Steam was The Orange Box. I remember that when I put the disc for the game in that it just started downloading the game from steam, which really pissed me off. Is there a way to get it install from the disc so I don't have to wait 600 years for the whole game to download?

Try unplugging your internet. <-Not trolling
It only needs to verify using steam, and you only need to verify once the game is installed.

You need to wait for that until it is unlocked on Steam iirc. Then you can enter your code and install from disc.

https://support.steampowered.com/kb_article.php?ref=5357-FSQM-0382

Open steam in offline mode and it should install from the disk.

dont have steam running when you put the disk in. install. if/when steam does try and download entire game after installation, pause download and verify game cache.

can it validate it in offline mode?

There will be some sort of download since we already have a day 0 patch.
It is unavoidable. But it is not that big.
And no, you cannot add Games in offline mode.

Unfortunately no, you cannot. So make sure you're on a computer with a stable internet connection when activating/installing it.

Thanks everyone for you help! I guess this thread is dead now.