If you don't have a microphone/webcam on your work computer you can join us by phone line. Think of it as 1) you sign in by video then 2) you call into the hangout by phone.
Here are the instructions.
1) Click the google hangout link and you will be connected to the call. We can't see you (you don't have a webcam) and we can't hear you (because you don't have a microphone - we're going to connect you by phone in a minute).
2) Click the "invite people" button (you're inviting yourself via phone)