Again I will say that a GFI is the only safe and to code way to put a grounded outlet on a non grounded system- as said, it must be labeled no Equipment ground, but it does not need a ground, and will protect anyone from shock even without an earth ground. Bonding the ground to the neutral is wrong and dangerous, adding a ground rod is probably OK, but getting a good ground is sometimes problematic, depending on the soil. Here in Florida a 10 foot rod is going in to the ground water.
At first I was not sure about a 240 volt gfi, but they are labeled 120/240 volts, indicating they will safely trip using 120 volt loads.
