I think they just told you one.
SPI = Serial Peripheral Interface, all you need is a serial in, parallel out shift register like the ones mentioned. There is no coding involved, the SPI clock moves the SPI data along the shift register and the select signal tells you when it's ready to use. There are no easily available 4-bit shift registers but if you daisy chain two 8-bit ones it will work exactly the same, you just ignore the extra four bits. It is at most a two IC solution with no other components required so a schematic isn't worth drawing. I'm pretty sure there are examples of daisy chaining more than one shift register in their data sheets.
Brian.