Custom icon on Quick Access Toolbar SW 2012

I see in the SW Help how to do this in CircuitWorks, but don't see a way to do it in regular SW.

I know that I can drag icons from the Commands tab up to the Quick Access Toolbar, but the icon I want is not listed in there, which is FIle->Find References.

How do I create a custom icon for the QAT?

Thanks so much in advance for your assistance!

SolidworksUser Interface