How do I alter the shape of my existing concrete steps?
I'd remove the current steps, and then consider putting in new concrete steps. Maybe stain them or used colored concrete or perhaps tile them. 

Concrete pavers aren't really designed for steps...and tend to be porous lower-grade concrete anyways. They make bricks for steps, but are a nightmare to maintain over the long haul as you are constantly re tuck pointing them--especially if you live in a freeze/thaw climate.