Firmware need to be the latest. The latest support program + firmware is always downloadable from our website.
Then, the serial output from your 496 needs to come into the serial receive on the EFIS-D10A (pin 22 on the DB25 connector, or pin 3 on the DB9). More details on making that connection can be found in our latest installation guide.
Then, just make sure your 496 is set to NMEA out and that the NMEA data rate is set to "normal". That should do it.