Although I have not done it, I believe that the answer is "yes", you can drive a bipolar stepper via an L293D from LinuxCNC via the parallel port. It will not be a particularly good or fast driver (for example, no microstepping, no high-voltage, current-limited driving), but you should be able to get it working. You will need to configure either stepgen type 7 or type 8 (I'm not sure what the difference is, see
STEPGEN for starters) to drive the H-bridges, rather than the more common step-and-direction interface.