As far as I know there’s no way to do this automatically in the template, however what I did was target the links via CSS and add an image to them in the editor. I.e.:
.our-feat .row_content a[href=”YOUR_LINK_URL_GOES_HERE”] h4 {
background-image: url(“YOUR_IMAGE_GOES_HERE”);
background-repeat: no-repeat;
height: 150px;
width: 150px;
line-height:300px;
margin-left:40px;
}*
And then you just target each link like that.
The tricky part here is though that you still need to include an image along with the link in Theme Options->Homepage options, but you don’t want it to show up. so I just did a transparent pixel (1×1 image).
You may also need to adjust the above in the mobile layouts of the stylesheet.