The important part is the generated html code, jass that is marked up with semantic html is much easier to add to the greasemonkey script.
For example, use <code class="jass"> to markup the entire script and use <span> tags with relevant class names to mark up each keyword. Check the wiki for a somewhat good generated html.
Just tell me what sites you would want to use it on, I've no problem with updating it ^^ Though, the site must already have a jass tag since my greasemonkey script doesn't include a parser on its own but extend already existing ones (roughly...), that's why the support varies across different sites.