Depending on your woes, you may need
1x butter knife
1x roll electrical tape
2x compact discs that suck
Step 1: So it's Broken in freakin' Half
Trust me, stick to this.
The problem with the drum pedal is that the plastic flexes again and again, inducing stress and flex, and ultimately weakening the structure. It's pretty much inevitable that this will break.
To temporarily repair a split pedal, or to prevent the flex that could kill your well used kit at any time, all you need to do is reduce pedal flex.
I used a thin flat butter knife. The purpose is to provide uniform reinforcement to the pedal. The tape will hold it together well enough for a night, and the knife will reinforce the pedal itself, preventing the damage from worsening, or holding the thing together if it's already screwed.
You know what they say: more tape is more better!