Well, I just couldn't wait to do it.
So I hooked a couple up while they were at lunch. I hide one under the home fashion designer's chair, inside the swivel part connects to the seat. Then another inside his receipt printer (they lazy ones kinda hide over in his area where they are less visible to customers). After about half hour of listening to 2 of them, I removed the one from the chair. Figured, since he knows nothing about computers, if he does locate where the noise is coming from I can have him keep rebooting printer, computer, signature capture device, etc...
Then once I exhaust those, have him shut the whole system down, he'll go nuts when it still goes off.
God I can't wait for tomorrow....
If he still can't figure it out, I'll hide another Annoy-a-tron in one of the hundred or so wallpaper books.