Hi Chris,
There are varoius ways to do it. You could for example have two wires between each slave and the master PIC. The master signals one slave at a time to to send the current position, and receives it with SERIN or SERIN2. When all 6 slaves are polled it sends the data to the master. The USART sends the data "true" so the master would need to receive it "true".

Another approach is to implement a RS485 network.

/Henrik.