I found a link to a site that has some of the song from 3rd Mix plus. If you are interested, here's the link:

Dance Dance Revolution 3rdMIX PLUS (AC) (Japan) - Simfiles - Zenius -I- vanisher.com -5th style- II (http://zenius-i-vanisher.com/v5.2/viewsimfilecategory.php?categoryid=344)

thx