You have to add this line to bspfilters.sam
AddFilter {AEFA5024-215A-4fc7-97A4-1043C86FD0B8},MatrixMixer
and then RENAME bspfilters.sam to
bspfilters.DAT
This works with BSPlayer 0.86, haven't tried with v1.0.
You can download the working bspfilters.dat file here:
http://www.hot.ee/reameez/bspfilters.dat