I don't have personal experience with IRDA devices myself. But as a general rule-of-thumb, PXI can be interfaced to any PC industry product through the many PC standard interfaces (ie serial, USB, ethernet, etc). I went ahead and did a search on google.com for "USB IRDA", and found several USB-to-IRDA converters in the under $50 price range. Just about any PXI embedded controller will have at least 1 USB port. Also, EKF (www.ekf.de) sells a cPCI/PXI Dual-port USB host controller module if additional USB ports are needed.
But at any rate, the general idea is to just use serial, parallel, usb, firewire, or ethernet interfaces.
Regards,
Greg Caesar
PXI Marketing
National Instruments