Nick,
I had a project a few years ago interfacing four Mitutoyo dial indicators with a basic stamp uc ,outputing the results on a lcd.The indicators used the SPC data output,which I understand does not have a standard protocol.Basically the uc pulls the request line low on the indicator,after a period of time it sends a clock pulse and data stream to the uc.The uc must shift in the data on the clock.This was not reliable using the basic stamp,it required an external shift register to work properly.Using a pic is easier,it needs only to use the interrupt input for the clock pulses.If you think this is what you need ,I can gather the info for you.The demo program I wrote in Picbasic pro inputs one indicator and outputs to the pic serial port.I have a document that describes the Mitutoyo output stream as well.

I didn't use the shiftin instruction,if I remember correctly it would it would not work because of the interrupt requirment.

Later
Paul