XLAM would be an Excel 2007 format. I do not know anything about running the add-in with 2007 (yet).
As far as I know, the only version available at the moment is the same .XLA add-in that has been available for the past several years.
I know there has been some work done on an upgrade of the HTML Maker for 2007, but I haven't heard anything about it in a while.