If you have a FET model , ( a good model) youcan use ADS to do DC tracing. if you dont have, you need two power supply, ampmeters and votlmeters. (all with labview interface or something that you can use computer controll). Connect a DC supply to Gate and a DC supply to Drain with an ampmeter. Then, you very Vgs at the DC Gate supply and vary Vds at the DC Drain Supply, plot the VI cure. If you use labview, you can automate this process and see a nice V-I curve in your computer.