There is an autolisp that I just love for working with curves to bring in to SketchUp. It is called qbrick. It can be found here:

I genereally use it to break all lines segments where they cross another lines segment so they come in to SketchUp cleaner. But it also works well with arcs and segments. Check out the last group of operations on the page. It looks like it lets you divide entities into segments of equal length. Hope it helps,

Chris