I haven't even used Mach yet, but I have done a little programming with the parallel port and unless anyone feels the need to correct me the, the pins on the parallel port are fixed, i.e. only some are inputs and only some are outputs, and an an input pin cannot become an out and vise versa.

This might be a little of interest...

http://www.codeproject.com/KB/cs/csppleds.aspx

Thats what you were asking right?

Dave.