Phase III power has 3 hot legs (120 volts each) out of phase by 120 degrees each, so the load is balanced, without the need for a ground (or neutral). In a 4 wire 220 cable you usually have 2 legs which are hot (usually red, and black wires) which are really 2 of the 3 legs of 3 phase line. The 3rd wire is usually white which is the neutral, and the fourth would be the green or ground wire. The neutral (white) is usually tied to the ground (bonded) at the service entrance main panel. Connecting to the two hot legs will give you the 240 volts required, but it does have to be grounded then. If the voltage is too low for your application, you might need a boost and buck transformer as well.
Consult an electrician to make sure it is all done to code, or contact your local electrical inspector where you live; death is a definite consequence of an improper connection.