Measure capacitance in softwire using Tina/Multisim/other simulators
Step a DC voltage with a fixed output resistance across the terminals. You should be able to do a transient analysis and estimate the time constant of the exponential voltage rise across the network. Time constant = RC, so if you know R, you know C.

If you can't do a step function, you're out of luck. You can't measure capacitance unless something is changing.