I'm not going to turn this into a thread of me talking to myself, but I wanted to say that I put a 24LC16 on the pic and I'm now reading the directory table into memory, working on it and writing it back to the MMC without any problems. The PC now accepts the modified files with the correct file information from the MMC.

Reading out of the MMC to the I2C takes ~3 seconds for a 512 sector. I'll be getting it faster by coding for loading the 16 byte buffer on the I2C.