[Hocrest]

How "temporary" do you want it?? The cheesiest way is to unplug the connector for the fan and run two wires from the battery (an inline fuse would be a good idea) to two diagonals of the four choices on the fan side of the wiring harness. If the fan runs backwards (pushes air out the front of the car) reverse the polarity.

This is in no way a long term solution, but it is the quick and sure way to get your car home. Unless it is real hot you should be fine with one fan, just don't drive the transmission real hard and don't use the AC.