Unearthing a password

We use Airport (wireless internet).

This computer (eMac, six years old) was initially set up so that either I or my husband could log in, and there were essentially two computers in one (his and mine). For example, if I logged in the desktop would appear as I configured it (screensaver, icon placement), etc. If he logged in, it would appear as he had configured it. (This extends to programs, etc.)

Initially we set it up that way because we planned to both use the computer. But in practice I use it the vast majority of the time, and he uses his work laptop. When he uses this computer, he goes ahead and logs in as me (he has my password) since many more programs etc. are on this one and since if he uses it for a short time, I'll still be the one to use it later.

Six years ago, though, when he didn't know that's how things would play out, he set up Airport when he was logged in as himself.

But since he hasn't logged in as himself in nearly six years, he has forgotten his password. He can't now log in as himself.

We can't access or change the Airport password when we're logged in as me.

We need to either figure out the Airport password or change it, to get our brand-new computer connected to the internet.

Any ideas for how to get around this problem? (Besides him remembering his password of course, which he has tried to do for two days now without success.)

Sorry if anything's not clear, hard to strike the right balance of providing enough but not too much info. Ask if you're still confused and I'll try to explain better.

Thanks!!

edit: we obviously don't know the Airport password either.

Problem one: we can't remember the Airport password (set up six years ago, not used since, and forgotten.)

Problem two: we can't remember E.G.'s log-in password (set up six years ago, not used in at least five, and forgotten), so we can't access the Aiport password on the Keychain or change the password.