FractalFusion: I noticed a couple of things that make it pretty obvious that you haven't seen my run, or at least you haven't seen it in a while.
There isn't much that can help you in it, since it's an old run, but it might give you some ideas.
http://speeddemosarchive.com/MegaManX4.html
Anyways, here is what you should know, if you don't feel like watching my run.
When you do the kuuenzan (the upgraded jump slash) with Zero, you can turn around to score extra hits. Turning around to get extra hits out of your slash is useful against the wall in Web Spider part 1, and Slash Beast's midboss.
Also, when Frost Walrus reaches the left wall and starts to stand up, you can hit him twice as he is transitioning from crawling to standing.
If you did Web Spider before Slash Beast, you would have been able to cancel your last set of slashes before Beast starts dashing into a Raijingeki (the lightning lance), which would have killed Beast.
Oh, for the colonel battle, test and see if you can make the first icicle take off half of his life. I swear I did that once, but I've never been able to reproduce the incident (I think it has something to do with him switching animations).
And yes, I know I'm being ridiculously picky and anal about this, but godammit I've played the shit out of this game. And I heard being picky and anal is rewarded on tasvideos ;)
Keep up the good work.