That's an interesting problem! Frankly, I would not recommend enabling html uploads on a wiki installation for security purposes (it's probably just as well that it didn't work! ) as it introduces a significant potential security hole into the system.
Also, don't feel bad that you couldn't decipher the code to put the form int the wiki page as described here, as that is a little misleading - the form is not really in that page at all , it is just a .jpg of a form used for illustration purposes.
The other potential solutions you investigated involving allowing html directly into the wiki text (input box - which says it requires version 1.5, and may not be compatible with the later wikimedia versions, and the html in wikitext reference) are, in my opinion, also less than desirably secure for many of the same reasons that allowing html uploads are potentially dangerous.
While I only took a quick google, I didn't find any "wiki-based" solutions to this; there may well be one out there- I just have not located it .
That said, I would approach the problem in a different way. Rather than trying to embed the form in a wiki page, I would either embed the form in the "skin" (template) of mediawiki (if you want it to show on every page), or simply build an "off wiki" html page(s) to house the form(s) related to your list management and a link back to the wiki pages, and link to those from within a wiki page wherever you want to make them available.
You could make them appear to be "part" of the wiki by starting with a "view" source of an "empty" wiki page, and save that as a "skeleton" for your static html page - just edit and include the form and tweak any links as necessary before saving.
Does that make any sense?