i've just done it !
it took me a while to find the perfect focusing screen
(here is the list of all focusing screen done by Pentax for MX and LX and their own application :
http://www.bdimitrov.de/kmp/misc/focus/screens/index.html )
remplace the standard mate screen by this one : microprism on the outer ring and split screen in the inner ring (Pentax SC-1).
Only one thing need to be done : just cut a very little slice of the botom side, on 0.5cm to fit it in the MZ-5n.
Now it's the same screen on my MZ-5n and SuperA.
Next week a great test : a huge party where i will shoot with DA*55, DA40, DA35/2.4, FA-j 18-35, Ilford delta 400@3200 iso, portra 160@1250 iso.
All i miss is a good 85/1.4 from say .... Samyang