You can use any amperage charger you want. The rating is only an indication of the max the charger can provide. It will only pull what it wants as long as the voltage is 5v. This is mandated by Ohm's law. The current drawn will be determined by the voltage (always 5v) and the phone's resistance (which doesn't change with charger).
The most the Incredible will pull is 1A. If the charger can put out more, it doesn't matter. If it puts out less, it charges slower.