Just did a quick proof of concept. Its a bit of a pin changing blades on the table saw so I was putting it off. Just used one of the dado blades (I don't recall how wide it is), but one blade was perfect.
This is in a crappy piece of wood, but it proves that I can make even grooves that hold both heroscape AND heroclix units (half the base removed). I just need some good hardwood to work with now and I can mass produce ladders! woot. I wish the heroscape unit held in a bit better...but this is mostly for CityScape which is 99% HeroClix...so this is great!
They come out to 1 rung per 2 levels of terrain...which I believe matches the official ladders.