I have tried to change the images on my site from img to svg, changing img tags to embed and object tags. Bu
You can have an onclick event in the svg itself, I do this all the time in my work. make a rect over the space of your svg, (so define it last, remember svg uses the painters model)
rect.btn {
stroke:#fff;
fill:#fff;
fill-opacity:0;
stroke-opacity:0;
}
then as an attribute to the rect add the onclick (this can be done with js or jquery as well).
<div>
<svg xmlns="http://www.w3.org/2000/svg" version="1.1">
<g>
<circle ... //your img svg
<rect class="btn" x="0" y="0" width="10" height="10" onclick="alert('click!')" />
</g>
</svg>
</div>
this will work in most modern browsers, http://caniuse.com/svg ...though if you need cross compatability, you can implement Google Chrome Frame. http://www.google.com/chromeframe