We've amanged from a PIC (16C57) into a PC parallel port in standard mode.
We use 5 input lines (including 1 IRQ line) and 2 output, though I forget
which preceise lines we use.  We have a simple protocol:

1. PIC places 4 bits on input lines to PC.
2. PIC raises IRQ line
3. PC IRQ handler takes 4 bits of data and raises an output line (we call
it a strobe line)
4. PIC sees strobe line rise, places other 4 bits on input lines and clears
IRQ line
5. PC sees IRQ line drop, takes next 4 bits, clears strobe line, ends IRQ
processing

We use the second output line to test for PIC presence on the port: if the
PIC sees that line go high, it sends a couple of test bytes to the PC.

Our application is complex and code cannot be shared: our PIC is gathering
data full time in a time critical operation and communicates with the PC in
limited time during certain phases of the operation.  I can get the LPT
line names we use tomorrow when I'm back in the office if anyone needs
them.