MP

Try this site: http://home.planet.nl/~meurs274/ Some stepper projects with Atmel AVR. I know you have the 89C51, but there is enough similarity that this should be what you need. Basically, your port pins send the pulses and the ULN2803A drives the signal. Very simple layout. Even has a board layout in eagle that you can edit with the free demo version.

You can edit the packages in Eagle, but I do not think it is an available option in the demo version.