If the HSC is set up for single phase, something like a simple switch or button should work, yes. Depending on the quality of the device, it may give multiple counts due to the contact bouncing slightly as it makes/breaks. However, this should be enough to monitor the value in the program and watch it count up.
If the HSC is set up for a quadrature signal, you will have to manually step through the waveform yourself, but it should still work in theory.