I found the answer; here is an example when the min is applied along the 3rd dimension:
>> [amin, aind] = min(a,,3);
>> [a1,a2,a4]= ndgrid([1:size(a,1)],[1:size(a,2)],[1:size(a,4)]);
>> allind = sub2ind(size(a), a1, a2,squeeze(aind), a4);
>> a(allind)-amin % ==> this would be all zeros, i.e. allind is the right index.