I got the game through Steam too, and I was able to find a PDF of the manual somewhere. I just can't remember where now.
Either it was installed with the game in some weird Steam directory, or I downloaded it somewhere.
People are right that it's not a great manual. But if you're like me, you want to take a look anyway.
When I get home tonight I'll poke around on my game machine. If I figure out where I got it, I'll follow up here.