How can I test a combination GFCI/circuit breaker?

My house has old knob-and-tube wiring with no ground. I've replaced the old two wire outlets with grounded outlets, and replaced the circuit breaker for the outlets with a GFCI/breaker, as allowed by code. How can I test at the outlets to make sure the GFCI is working correctly, since there's no convenient source of ground near any of the outlets? A friend suggested using a "suicide cord" and a 20k resistor to ground, but I'm a little wary of doing that.