2 pins sounds unusual for a stepper motor. Do you use a wave drive and select one of four coils with the 2 pins?
Maybe you could use the DACs to build a microstepping drive. The ARM core and the 1 Msps should be fast enough for implementing some nice controlling application, with soft start etc.
You will need 4 pins (in case of bipolar) or 6 pins (in case of unipolar) to sequence the stepper motor.
But PSoC5 will not drive the amount of current required by the stepper motor. So, using a buffer such as ULN2003 will help in this situation.
Sounds like the OP may be planning to use a canned stepper drive circuit, most of which accept STEP and DIR (direction) inputs as digital signals.