You can always make your m/s matrix manually as a 3-track in any software that supports > 2 mono tracks, stereo panning, and phase inversion.
Just split to mono tracks, and then copy and phase invert the side track. Mix the 'mid' track panned center, with 'side' (+)phase panned left and 'side' (-, inverted) phase panned right (assuming the positive lobe of your fig. 8 was 90 deg. left of center axis). Keep the levels for your two 'side' tracks even and adjust their amplitude relative to the center-panned 'mid' track until it sounds just right.
Thought I'd bump this useful thread as I +t everyone.
I just did my first m/s recording here @ home and wasn't sure, off the top of my head, how to mix it.
I record in Reaper (Great, low-cost, DAW) & I have ToolsOne but I don't really dig what it's doing when I use it. So, I downloaded MSED for future fiddling and then I read thoe quoted post from easyjim. This worked great and I really like what I'm hearing. Wish I had rehearsed better but, You gotta record when the moment arrives, around here (read: when the kids aren't home.)
Anyway, here's the setup:
acoustic guitar w Cascade Fathead (side) + Superlux SMK-H8K/U (mid) > Tascam FW1804 > Reaper
I also ran a third channel with a soundhole pickup out of habit but I hear far less need to mix it in than I usually do when I mic the fretboard and soundhole as I usually do.
Anyway, Thanks.