  We describe how the Schroedinger functional and twisted mass QCD can be used
to compute the kaon B-parameter B_K on the lattice with Wilson fermions. This
new approach is expected to reduce the systematic uncertainties on B_K through
a better control of its (nonperturbative) renormalisation. Preliminary results
for the bare matrix element in a physical volume of (1.5^3 x 4.5) fm^4 are
presented. The renormalisation of the matrix element in a Schroedinger
functional scheme is also discussed.
