Can Linux configure the serial devices automagically?

Yes. To get Linux to detect and set up the serial devices automatically on startup, add the line:

/etc/setserial /dev/cua* auto_irq skip_test autoconfig
to your /etc/rc.local or /etc/rc.serial file. Do this for every serial port you want to auto configure. Be sure to give the correct location of where your setserial program lives, and give a device name that really does exist on your machine.