you can probably use greasemonkey somehow to add new buttons to the text editor to insert whatever html you need in a post.

@Francis: Doable, but the HTML code that makes the editor is pretty complicated and it might take time to make the script edit it.
Currently the tags are working, but they only have an effect in the main post of a topic, seeing as replies don't exist in the source code until the expand button is clicked. Again, this is probably fixable but complicated.