I got that code following the Master Conference 2008. At that time you had to sign paperwork because of the propritary nature of the SD (like USB, Bluetooth, Zigbee etc.) allows for its members. The SD interface for Microchip was limited to the slower method of transfer and non-HD at the time. But as stated there is information on their site. I probably still have the FAE name if you need. Also the forums on the Microchip site have a lot of people who have implemented SD and are very willing to help.
It is also written a book about this "Sd Card Projects Using the Pic Microcontroller" By Dogan Ibrahim. But this book is based on the PIC18F series. If your SD card support SPI It should not be that hard