This shouldn't be any problem at all.

There's a great (if a bit technical) description of the whole process here:

http://technologyinterface.nmsu.edu/...r/printer.html

The gist of it is that the pushbutton input will appear on the parallel port's 'status' register. So if your port is set to address 888 (0x378), you can tell DirectRT to look at the status port (0x378 + 1 = 0x379) and you'll be in business.

Note that parallel port pins are only slightly buffered, and don't tolerate short circuits well at all. So double check your wiring before connecting anything.