I believe the ethernet IoT card will automatically show up without any configuration because it's USB based. You may have to take the IoT slot out of reset though. I'm not really familiar with the FX30 so I don't know which IO is connected to the IoT slot reset pin and thus I can't say how to control it.
This information should be in the FX30S user guide on page 58 under the table
IoT Connector Interface, but it's missing. I dug around a bit in some internal documents and it seems like it might be connected to GPIO6. So you could try this to take it out of reset:
echo 6 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio6/direction
echo 1 > /sys/class/gpio/gpio6/value