There's no reason why not, taking into consideration info people have put in this thread.
The only real difference between rope and wire is that rope is more likely to be of thicker diameter, this will probibly make it's removal more difficult.
If it were me, i'd be inclined to go to my local hardware store, they will probibly have steel braided wire there, no less than 4mm diameter is what you'll need if your supporting a human on a couple of wires. The store should be able to quote the wires strenght usually in Kilo's.
One important thing here for anyone thinking of suspending people from wires is that a human actor should not be subjected to a shockload on wires, this 'could' cause serious injury - at the very least they should be suspended from a 'Full body harness' via the wires and of course 'SAFETY' is the most important thing here - If in doubt, dont try it. Contact your local theater group, they should have people who deal with this kind of thing for show's they put on.