  We present a systematic method for constructing manifolds with Lorentzian
holonomy group that are non-static supersymmetric vacua admitting covariantly
constant light-like spinors. It is based on the metric of their Riemannian
counterparts and the realization that, when certain conditions are satisfied,
it is possible to promote constant moduli parameters into arbitrary functions
of the light-cone time. Besides the general formalism, we present in detail
several examples in various dimensions.
