Writing texcoords in domain shader

I’m working on a MaterialExpression and would like to pass data computed in the domain shader to the pixel shader. I could use CustomUVs if I computed the data in the vertex shader. Recomputing the data in the pixel shader is not possible because a uniform buffer bound by an external library is not available in the pixel shader. Is there a way in FHLSLMaterialTranslator to write out data in the domain shader?