How would I create a symbol and use it as a button to select a part of a SVG file?

Looking at the following example, if I wanted to create symbols (and use them as buttons) how could I use them to select parts of the shirt?

http://www.edgedocks.com/market/geek-shirt-designer-svgphp-edge-animate

In other words, instead of clicking on the shirt, I want a button symbol off to the side that would say "shirt" and do the same thing.