OS X :: Manually Create Airport Password?

Here's one I haven't been able to find despite some Googling and playing around:

I'm creating a disk image for a school to use on all their new laptops. It's not a fresh install. There are some customizations and software that's being installed (Volume License Office, for example). One of the requests that came in from the school was to have the wireless network password already stored on the computer so students wouldn't have to ask to connect. It would "just work."

I played around in the Keychain Utility with creating an Airport password manually, but couldn't figure it out for sure. I wanted to know if anyone has procedure they use to do this and if you could enlighten me on how to do this.

I feel like it shouldn't be too hard and maybe I'm missing something very, very simple.

The only caveat is that there are multiple accounts on the laptop (Administrator, Teacher, Student). Ideally the wireless password would exist for all these accounts and automatically connect upon startup/login.