David, it's a simple process.
The load can consist of a single resistor. Something like Mouser part # 284-HS100-10F. It is a 10 ohm resistor rated at 100 watts. (about $12).
The NEMA 23 motor that Inventables sells (part # 25311-03) is rated at 3.2 volts and 2.8 amps per phase.
The NEMA 17 motor (part # 25253-01) is rate at 2.8 volts and 1.68 amps per phase.
The gShield is rated at 2.5 amps per phase with proper cooling.
NOTE: The NEMA 23 stepper motor can draw more current than the gShield can supply so if you do this process make sure that the current limit pot is set to it's lowest current setting and slowly move up to the current limit that you want.
For the standard 24 volt supply: i = v / r = 24v / 10 ohms = 2.4 amps; p = i ^ 2 * r = 2.4 * 2.4 * 10 = 57.6 watts.
I like some headroom on the power dissipation and the 100 watt resistor only costs a few cents more than a 75 watt.
If you plan on running the gShield at the 2.4 amps you should check with the gShield providers to find out what "proper cooling" means for them.
So the test setup would be to disconnect one of the stepper motors from the gShield. Run one wire from one of the coil connections through an ammeter then through the power resistor and then back to the other connection for that coil on the gShield.
You might have to use something like the Universal G-code Sender to activate the stepper motor, but that should be obvious if you don't get any current through the ammeter. I don't know if you can do this through Easel.
It 's much harder to describe than to do.
If a drawing is needed then I can do that, just let me know.