you can just insert the jquery itself, which is very easy.
all the plugin was doing was inserting 3 lines into your header, nothing fancy or codey.
http://www.appelsiini.net/projects/lazyload
once you download the files from there just insert this into your header, using your own location for the lazyload.js and the grey.gif (or whichever image you choose):
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js" type="text/javascript" charset="utf-8"></script>
<script src="jquery.lazyload.js" type="text/javascript" charset="utf-8"></script>
<script type="text/javascript" charset="utf-8">
$(function() {
$("img").lazyload({
placeholder : "grey.gif",
effect : "fadeIn",
threshold : 0
});
});
</script>