Attached Link: http://koti.mbnet.fi/~ilaripih/MPEHome/

You can always use Mat Pose Edit to convert MATs from one poser version to another, it's free and available from the above link. That's the easy way. If you want to learn about what you're doing (good thing IMO), you have no doubt bought P4/PP product, yes? Open up the MATs in a text editor and compare to a P5 MAT.

Create Poser Mats for free in DS3