How to construct multi-tiered (layered) fuzzy logic systems

I'd appreciate any advice on how to construct a multi-tiered fuzzy logic system. I have 4 different categories of input variables. Each category has a single output. I could create 4 different fuzzy logic models and map each class of inputs into an output. A 5th fuzzy logic model could receive the outputs from the first four models and return the "grand" output that I desire.

Any advice on how I can do this without using Simulink? I'd really like to be able to do this within the GUI environment so that I can do "real-time" demonstrations to colleagues and show the ultimate consequence of lower-level changes in membership functions.

Thanks.