can I use the Parallel port A as input on a Rabbit 4300 prototype board?

I am trying to use the Parallel port A on a Rabbit 4300 with the prototype board as in input (in particular want to use PA0 and PA2…)
Is this possible? What do I need to do to set up the board correctly. I tried sending 0x00 to the SPCR, but something seems to override my applying zero voltage to these pins.