You want to have as little forward momentum and to jump at the front of the part with the checkpoint. If you do it right, you should make it without dying, though it's for more precise than I can describe, and you're just going to have to keep trying until it works
Alternatively, here's a video showing the whole level, in case I missed which part you mean:
Alternatively, here's a video showing the whole level, in case I missed which part you mean:
Deathchill