I need a way to include other HTML content, such as footers for press releases, that can be easily applied across multiple HTML modules similar to the way a Server Side Include works.  I've tried adding Javascript to the HTML module to modify DOM elements using <div> id, but when saving to DNN5.5, it strips out the <script> code.  I have this code working correctly in an external HTML file. 

I've also searched for information in the DNN documentation and the web on how to do this and also looked for modules to perform this function, but haven't found any.  This seems like a common capability for website development.  I don't want to add an additional HTML module because it can't be inserted into existing content and can only render top, above, below, or bottom of the static HTML module in the panel/container as a separate, distinct HTML module.

How can this capability be implemented?