You can fit most seats with some work. All that's needed is a rail to attach it to the floor.
Can be done many ways. If the fittings are a close match you could use the rails off of the stock M2 seats.
Only thing I'd look out for is the width on the MPS seats.
I looked at a friends st and the they use the same bolt locations on the chassis. The ST seat does have a side airbag and will be fairly heavy. Not sure if you could get the airbag to work with teh mazda system though
I think planted has different part numbers for the 2 and the ST. I have Cobra seats in my 2 and I was wondering if they would fit in the ST. I haven't researched it further. There is some info on my seats in another post if you have any interest..