Wow did I solve my problem today. I went to Best Buy and bought a set of Logitech V20 notebook speakers. I plugged them into the USB port on the back of my Cinema Display. OS X recognized them in the sound control panel immediately as Logitech USB speaker. When I want to use the iMac's built in speakers I select the internal speakers option, when I want to use the Logitech speakers I simply select them in the same sound control panel. Everything works perfectly and I did not need any other software as I first thought I might. The bonus is that the sound quality coming from these V20 speakers is terrific. I couldn't be happier, nor could it be any easier to do or work any more perfectly.
The volume controls on the speaker control the volume in OS X without any problem, I have not tested the other media playback buttons yet but suspect they too will work just fine.
I was able to put them on their sides and they fit perfectly under my Cinema Display, I didn't have to take up any more desk space at all to use these. Finally they are a silver and black combo which match my Cinema display just great.
As you can tell I am excited with this arrangement and hope it helps someone else who might be trying to solve a similar problem.