Most scripts can be combined with iframes. The advantage is that you can position the iframe just where you want it and then have your actual script in an external page that the iframe loads on page load. This allows you to test your script too, some scripts don't live happily on a page with other scripts. When you put scripts in iframe the header information stays on the external page as well as the body content. A plus to this is if you are hunting on a regular basis in your html code to find anything you need to edit, there is less to search through. If your script encorporates a menu that appears on several pages, you update your external file and all your pages that use the external page in an iframe are updated automatically.
Some scripts don't have absolute positioning. You can experiment with code that comes from other scripts that uses absolute positioning and add it to the header as the borrowed script. Sometimes this works, sometimes you get NOTHING. But you can undo. It may be time consuming but you gain a by-the-seat-of-your-pants approach to working with scripts just by playing with them.
Many scripts are able to combine and make an effect you can't find one script to do. So they are fun.
:)