As I didn't find the attachment in your post, I have modified the default Slave FIFO firmware (attached with AN65974) by changing the BULK endpoints to Isochronous endpoints. The MACRO "ISOC" will enable the isochronous endpoints in the firmware.
Please let me know if this helps
SlaveFifoSync.7z.zip 537.1 K
Thanks RashiV for the reply..!! Since only end points were changed there comes error in data transfers.