I guess he is talking about those buttons.
-------OT:
You can use CSS Attribute Selectors to do so by css only Add the following in your css file

PHP Code: 
a[href*="google.com"] {
    
backgroundurl("http://i.imgur.com/K2qXO.png"no-repeat;
    
height24px;
    
width24px;
padding5px 25px;

That search for google.com in each link and if found, it adds a image before that which is http://i.imgur.com/K2qXO.png in above example

You can change those to your hosts and replace image link + width if needed

Example: http://pastehtml.com/view/bs9pyum2h.html