Any self – emptying, tipping rain gauge that has a reed switch can be hooked up to the system. I modified a cheap wireless rain gauge from Accurite I found at Home Deport for $25 on sale. open up the case and hook up two wires to the reed switch and connect that to the rain count input of the system. If the bucket is of the wireless kind make sure that you connect the two wires with the correct polarity to the system. With a voltmeter measure the voltage across the switch and connect the minus to the ground of the system.
The station can be calibrated to the tipping rate of the particular rain bucket, but it is best to also calibrate the bucket itself (little adjustment screws) to what the manufacturer says it should be. Mine was horribly off at first.