I had this issue in the past when I used MxComment on a community site I developed and had to hack the Mamblog component to get it to work right. If I can remember what the hack was (or if I have a backup of the site) I'll try to look it up and post it.
--edit--
Nevermind - didn't realize you had already posted a solution
--end edit--
We ended up going with MyBlog because I thought it was a better component (and still cheap for an enterprise solution). As a side note we are also using JomComment on that site as well. I love the AJAX posting and updates and wish MxComment had the AJAX features, but MxComment is a much more well-rounded component (read more, social bookmarking, rating, etc).
That being said, I still use MxComment on my own personal site.

<br /><br />Post edited by: joshua.lyon, at: 2008/01/15 20:35