Has anyone interfaced a PIC to a V2DIP1 module using EUSART?

I am retrofitting a dual USB port into an application by using the V2DIP1 module from Vinculum. I am running into problems trying to interface my PIC 18F2550 to it with the PIC's USART interface. Has anyone on the forum used a USART interface to communicate bilaterally with a V2DIP1 module? If so, I would like to collaborate with them.

Since the V2DIP1 also supports a SPI interface for MCU communications, I would also like to collaborate with anyone who has interfaced using SPI. In particular I am wondering which way is the best/easist way to go when using PBP to program the interface.
John