It all really depends on the kind of sounds you are trying to duplicate. Stinson and Donald used quite a few digital synths (Roland D-110, Kawai K1) the sounds of which are difficult to reproduce without sampling. For example, the sound at the start of Hydro Theory is based on one of the spectrum loops in the D-110. The only thing I can tell you is that you can get close with additive synthesis, but the actual sound relies also a lot on what the guys at Roland did to store the sound in the D-110 The human voice ah sound that you can hear on some tracks is a preset sound of the K1, etc… You can find info about this on Gearspace for example.
Keep in mind also that they relied a lot on the Alpha Juno, the MKS-80 and the Pro-One. The Alpha Juno is simple but it has features that make it quite peculiar soundwise in my opinion. First, the oscs in the Alpha Juno can produce a saw ring modded by a a square wave one and three octaves higher. The same circuit is used to perform pulse width modulation on the saw. If you can do this kind of thing on the MnM (I do not have one), then you may get close to the Alpha Juno sound. It is quite easy to dial in many of the basses Drexciya played with this synth. The Juno chorus has a sound of its own. Finally, the sub osc is quite rich in terms of waveforms, with square waves at different pitches and with different widths.
The MKS 80 is a Jupiter 6 in a box if I am correct, with a boost in the bass department. Have a look at what a Jupiter 6 can do soundwise, and it will probably give you some ideas regarding sound design.
Finally there is the Pro-One. Modulation in this synth is quite wild (I remember reading someone, I think it was Urs Heckmann from U-He, stating that mods can cover a 12-octave (!) range for filter cutoff). Also, you can both sync and FM the oscillators. Again if you can achieve this on the Mnm that may help.
Of course, I cannot guarantee everything I have just said is 100% accurate, it comes mostly from my experience trying to do the same thing as you are trying to do. Go for it, I have learnt a lot myself doing this! Keep in mind also that Drexciya’s sound relies a lot on the fact that they would play the tracks live in the studio (at least part of them), giving them a rough edge, and that there is quite a bit of saturation and distortion going on too!