Constructing structures using CREME-MC stacks

I would like to create FinFET structures using CREME-MC layer stacking method, but it seems that CREME-MC tools do not allow horizontally interleaved layers of different materials. The current CREME-MC appears to work for only vertical variation (thickness) of device materials. Do you have any suggestions/recommendations on how to vary stack materials horizontally? For example, if I wanted to have three adjacent layers of oxide -- silicon -- oxide as one stack, CREME-MC would not let me do that. It defaults the sidewall materials (for example, the oxide in the above-mentioned example) to Silicon.