  We introduce a new parameterization of four-fermion operator matrix elements
which does not involve quark masses and thus allows a reduction of systematic
uncertainties. In order to simplify the matching between lattice and continuum
renormalization schemes, we express our results in terms of renormalization
group invariant B-parameters which are renormalization-scheme and scale
independent. As an application of our proposal, matrix elements of DI=3/2 and
SUSY DS =2 operators have been computed. The calculations have been performed
using the tree-level improved Clover lattice action at two different values of
the strong coupling constant (beta=6/g^2=6.0 and 6.2), in the quenched
approximation. Renormalization constants and mixing coefficients of lattice
operators have been obtained non-perturbatively. Using lowest order ChiPT, we
also obtain <Pi Pi| O_7|K >^{NDR}_{I=2} = (0.11\pm 0.02) GeV^4 and <Pi Pi|
O_8|K >^{NDR}_{I=2} = (0.51\pm 0.05) GeV^4 at mu=2 GeV.
