Hmm, I think its like the HTML codes for a image to be a link. I'm not sure about the codes. Its like <img src="link of the itunes pic" link="link to the radio>. That's not the right codes but it's similar. First, you need to get the itunes picture for your site. Then upload to server and then, put codes in wala. Actually, I found it. Rofl Lmao. Ok...
<A HREF="http://youripaddress:yourport/listen.asx"><img src="http://www.yoursitehere.com/images/itunes.gif"></a>
If you need more help, just contact me. You will need to get something to link for the itunes thing. It usually doesn't work. I'm not sure how to upload your radio to itunes or something but give it a try.