I was curious about how hard it might be to drive a Dallas DS1267
from a PIC, myself.  The dalsemi.com web site has a PDF data sheet which
explains what you need to do to set and read the pot's wiper.  I may be
misusing the term, but it looks like a SPI.  One wire for data in, one for
clocking those data, and one wire out for data;  nothing unusual.  I haven't
gotten one yet so I don't have any code, but it looks like the code should
be trivial.  Now I have probably forever cursed any project I might ever
build with the DS1267 by saying this.  The pdf file you want is 1267.pdf
and it gives connection as well as operational data for all package styles.

        One neat thing for those watching their pins dwindling away, it is
possible to run a whole string of DS1267's in a daisy chain.  You have to
output a 17-bit string for each pot so the number of bits that must be marched
out of the data wire is 17*N where N is the number of DS1267's you are
working with.  The serial data rate can reach 10 MHZ so most PIC's should
be able to pump data in as fast as they can without any worry.

Martin McCormick