Hi Sean-
This functionality is theoretically possible, but this might not be the best option if you are concerned about latency in operation. A few references for using the parallel port in LabVIEW are linked in
this thread.
If you are concerned about precise timing and operating system latency issues, you may want to consider a hardware-timed PCI counter/timer board instead.
This utility is a good starting point for selecting such a card.
Tom W
National Instruments