sure, just take the Z component times 0.2 or 0.3 or so and add it to either the X or Y depending on the direction you want. and also apply the same tiling factor as well before doing the 0.2 or 0.3 so its in the same scale.
A simple method like this is referred to sometimes as a z shear. oftentimes the same method is used to make a tiling 2d texture into a psuedo 3d texture by applying a psuedorandom Z offset instead of a lienar Z gradient like you will be doing.