You could try using DKCRE to edit the level so that the jumproll is right at the start... but I'm not sure that's what you are looking for.
Also, the tank track platform is essentially on a hard coded path, and will not start mid-sequence. You would need to manually hack that, too, if you wanted to do this with the track platform there.
DKCRE isn't capable of starting the level in arbitrary locations yet, either, but there exists documentation here that could help with hacking that.
Finally, edited games won't guarantee an accurate speed run, so be careful about that.
