  We describe a general method for algorithmic construction of G-equivariant
chain homotopy equivalences from non-equivariant ones. As a consequence, we
obtain an algorithm for computing equivariant (co)homology of Eilenberg-MacLane
spaces K(pi,n), where pi is a finitely generated ZG-module.
  This result will be used in a forthcoming paper to construct equivariant
Postnikov towers of simply connected spaces with free actions of a finite group
G and further to compute stable equivariant homotopy classes of maps between
such spaces.
  The methods of this paper work for modules over any non-negatively graded
differential graded algebra, whose underlying graded abelian group is free with
1 as one of the generators.
