Transcritical CO2 in cascade

edit

Has anyone tried to model a Transcritical CO2 System in cascade like this one (last page)?

According to the "Input Output 9.1 Reference" I need a Refrigeration Gas Cooler but I would like to use a Cascade Condenser instead. However, if I try to use a Refrigerant System in cascade I cannot use CO2 (R744) as refrigerant.