Typically, this is done with microcontrollers that are programmed specifically for the control in question. This is because PLCs will be too slow and Labview will be to complex and not allow autonomous movement.
Also, using stepper motors without sensors (open loop) for joints is unlikely to be robust.
You may want to study various successful bipedal robots that already exist for some hints. Two examples I can think of are the Bioloid Premium (about $1k,) and the Darwin-OP (about $10k.) Both use closed-loop joint control with high-performance servomotors, and a microcontroller to drive the servos.