B757-300 FLT CREW HAS A RWY INCURSION AT PBI.

Narrative

TWR/GND (COMBINED) ISSUED A CLRNC TO TAXI TO RWY 27R FOR DEP. THE CAPT AND I HAD ANTICIPATED RWY 9L FOR DEP. THE ARPT WAS TURNED AROUND AFTER WE CONTACTED CLRNC/DELIVERY. I INFORMED THE CAPT THAT I WOULD NEED TO RELOAD NEW TKOF DATA INTO THE FMC FOR RWY 27R; AND THAT I WOULD BE HEADS-DOWN. I ASKED IF HE WOULD BE OK. HE SAID YES. I WAS HEADS-DOWN FOR NO MORE THAN 30 SECONDS AND THEN ANNOUNCED I WAS BACK UP. THE CAPT THEN TOLD ME HE MISSED THE TURN TO THE PROPER TXWY. I SAID STOP; BUT HE VENTURED BEYOND THE HOLD LINE AND ENTERED RWY 31-13. ATC NOTICED OUR MISTAKE AND INSTRUCTED US TO TAXI DOWN RWY 31 TO TXWY A; TXWY B; AND TXWY C TO RWY 27R. WE DID SO WITHOUT FURTHER INCIDENT. ALTHOUGH RWY 27R WAS THE PRIMARY RWY; IT IS MY BELIEF THAT RWY 31-13 WAS ALSO IN SVC. I WAS DISORIENTED FROM BEING HEADS-DOWN. I DO NOT UNDERSTAND WHY THE CAPT CONTINUED ONTO A RWY DESPITE MY OBJECTION. KPBI WAS UTILIZING COMBINED TWR/GND SVCS AT THE TIME OF THE INCIDENT. IF A DEDICATED GND CTLR WAS ON DUTY; THE MISTAKE MAY HAVE BEEN CAUGHT SOONER.