There is a LVFPGA core for SPI in VIPM. Actually we have a few, but I would recommend "NI SPI IP" version 1.2.0.1. It is just the SPI code and nothing on top of it. The product description says that it uses FTDI so you might want to also look into "FTDI Driver API for Serial Communication" package on VIPM but I have never used that one.