Awesome question, I saw this on ebay one day so I know it's possible. I think you have found me something interesting to do today. I'll update if / when I find the resource. I realize that most of us would use this for the betterment of our wallet but what a great charity thing this would be. Get everyone involved to download the toolbar and when it's used money goes to your organization.
This is NOT possible.. At least that what's they told me... But they will consider it in the future But maybe if you'll ask them to we will be allowed to do this rather sooner than later