Got the image markup half-working
Worked on the IMT interactive image output in XHTML, the last major portion of the site to be converted to the new system. First, I took the IMT's own web_view output code and started from that. The XSLT there expects to create a full page, whereas we're now rendering everything inside a framework created by index.xsl, so I had to abstract the IMT XSL into two named templates, one of which places CSS and JS in the header, the other doing the body content. That was straightforward.
Next was camelBacking all the actual code (XSLT, CSS and JS) to fit our new Mariage standards. That was tedious but not hard.
Finally, conversion involved making customizations to the XSLT to match what's needed on our site.
The result is something which looks monstrous at the moment (the CSS clashes with the core site CSS, and the font size problem is obvious), but it all works, and it shouldn't be too hard to massage it into something that looks good. I reckon about two to four hours should have it working. Then we'll have a fully-functional site using the grey.css file, and we can go on to look at the other optional stylesheets.