I think this was addressed here, and it looks like SSI may be the only way to go.

Hello.

I have a blog that uses categories and individual and category archives.  In the individual archive template for entry XYZ, I'd like to have a list that displays all the entries that share the same category as XYZ.

I've tried various things and can't seem to get it to work.  MTArchiveList doesn't have a category-specific parameter (you can only direct it to use a particular archive type). I would think that one would use (or <$MTArchiveCategory$>), but I think something in that particular nesting doesn't make sense to the system.

Any help?  I'd like to do this without resorting to SSI.