You often see circuit ideas in the mags for devices powered from the PC's parallel port - so this should come as no surprise!

The Triscend E5 Development Platform User's Manual has schematics - including their connection to a PC parallel port for JTAG.
Perhaps you could take a look at that for ideas?
See p56 - J3 (at bottom left) is the parallel port connector.
http://www.triscend.com/products/prod_doc.htm