You've probably realized that both jQuery and MooTools use the $ function to call up their routines. Fortunately, jQuery is actually namespaced so the $ function is free for MooTools to use. In other words, you may substitute the "$" used in the first jQuery call within a script segment with the text "jQuery", and both jQuery and MooTools code should work just fine. That's what I've used in the code below. Or, if you really want to be on the safe side, just replace the $ in all of your jQuery code with the text "jQuery." Finally, the jQuery site recommends that you add the noConflict() function at the top of your first snippet of jQuery code.
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script type="text/javascript">
jQuery.noConflict();
//jquery stuff
(function ($) {
$('p').css('color', '#ff0000');
})(jQuery);
</script>
The first line loads in the latest version of the jquery.js library from the jQuery CDN site. If you're using v8, this line is unnecessary since it has already been included. The rest is a jQuery script that changes the color of everything on the screen that is within a <p> tag to the color red.
For more information about the jQuery noConflict function, please see: http://api.jquery.com/jQuery.noConflict/