[HardDrive]

I'm looking for advice on how to set forms for a concrete staircase against rockery. The rockery walls curve up parallel to each other, and I would like the stairs to met up with the rock surface. Anything to avoid manually carving the ends of the forms to meet the rock would be nice. Maybe something with expanding foam insulation, then carve the foam?

I've seen this done in number of places in my neighborhood, but mostly with older houses. I know its going to be lots of manual labor, but its a small stair case, I don't mind. It creates a really cool look.

Any thoughts, ideas, alternatives would be most appreciated.