Hi David,
I'm not too familiar with IrDA, but from what I understand an IrDA interface can be installed as a COM port. How does the IrDA interface show up in your system?. If it is installed like a serial port, there will be a COM port entry for the IrDA interface. In this case, the IrDA interface will behave like any other COM port and you should be able to use it in CVI with the RS-232 function.
If it shows up like a custom device, then you'll need some kind of driver and access those functions from CVI.
DiegoF
National Instruments.