Hi,
As the Pics Usart modules are fixed at 8 or 9 bits only and the x/y coordinates are being sent as 16 databits then the only way I can see it could be done is to write your own software serial link.
If you search for Bit Banging you will find some examples where chips have run out of USART ports, or simply don't have any usarts, so software usarts have be written to fill the gap.
They will probably all be in 8 bit mode, but sure it will guide you as to how to make it acceprt 16 bits.