240 is still considered single phase, but your breaker box should have two hot leads feeding it, typically one marked black and one red. you'll likely have two rows of circuits in the box, and at the top of each row the black will tie into one side, red the other side. that's your 240. you'd need one circuit from each side. plus a neutral. and a ground. four wires.
but im gonna go ahead and say call an electrician. or pay a few bucks to one of the online services where some master electrician will answer your question if you give them details/photos/etc of your circuit box and wiring. they can at least tell you if its possible by looking at it. if it is, then i'd definitely say to call the electrician and get it wired up cuz you dont sound like you know what you're doing. that's not to be mean, its just a matter of safety.
