i think what he is saying is that the mr2 has a defective tyre and needs to put the golf spare on to see it through mot.
if so:
MR2 MODEL YEAR 91 to 99, PCD 5x114, OFFSET 35 to 42, BORE 60.1
Golf III 5 Stud MODEL YEAR 92 to 98, PCD 5x100, OFFSET 35 to 42, BORE 57.1
so in answer to the question, no, it wont fit. pcd on the mr2 is bigger than the golf and also the centre bore is bigger on the mr2.
taken from this, quite handy site
http://www.street-racers.co.uk/modifying_guide/for_alloy_wheels.htm