Microstepping with LM293

Can I use PWM on the enable pins as opposed to the input pins of a driver LM293 chip to achieve microstepping?

You don't mean LM293 (a comparator chip), you mean L293D.

I don't think you can do very well with this approach - microstepping uses current control
normally, but it might somewhat... It all depends on which decay mode is used, slow
decay mode being the worst.