This method could be used with a DB25 connector, a DB36, or any other angled PCB mount socket. My example uses a socket and cable with a 36 pin Centronics connector, as found on many old printers, because that's the kind of cable and socket I had from a printer I took apart. If you want DB25 like a standard computer parallel port, it's pretty easy to find an old motherboard with one of those sockets that can be used in exactly the same way.
1 DB25, Centronix 36pin or other PCB mount socket that you want to adapt to a breadboard.
1 40 pin IC socket, preferably the kind with flat tabs, though the machined pin kind may work
Zip ties (optional)
Needle nose pliers/tweezers
Solder sucker or desoldering iron (if your plug is currently attached to a board)
Step 1: Desolder and crack the socket
So, getting on to that, take a pair of pliers and crack up the plastic on the back of the connector. Since it comes to an angle behind the connector it breaks away pretty cleanly. If you want to be really neat about it you can file off the rough edges left where you broke off the plastic surrounding the pins.