the script: paste in the place where you wanna have it
<script language="javascript" src="http://gpcstuff.googlepages.com/random.js"></script>
<a name="mylink" onClick="rand_link()"><img style="cursor:pointer;" src="http://GPCstuff.googlepages.com/random_02.gif"></a><a href="http://GPCstuff.googlepages.com/randomproject"><img src="http://GPCstuff.googlepages.com/random_01.gif"></a>

Example: