Hello,
The ADS diode model will work for a Schottky contact. To my understanding the diode model will work for any diode which exhibits a non-linear I-V ~ I=Is e^(Vd/nVt). In the ADS schematic you will have to include the diode model parameters and fill in the appropriate values for a Schottky contact: Is, Rs, Cjo, Vj, ...etc.. Data sheets for existing Schottky diodes on the market could give you starting point for these values if you don't have a specific contact area, substrate, and doping level you must use.
Hope that helps,
Sami