There are also Pythons in the Free stuff area to so MAT poses.  Just make sure they specify a MAT for a Prop, as I thnk there is a differnece.

MATs were kind of done away with, with the advent of the material room though.  I'm kinda surprised you want to use one.

If i'm not mistaked a .MC5(Material Room Preset) is actually very similar to a MAT.pz2.  I bet if you ask the right person he/she will tell you that you can just change the extension of the file, or copy/paste a section or two, from a .MC5 into a .pz2!