Crawling movement mode help?

Hi, I’ve been playing around with the custom movement mode command in Character Movement, but I don’t know how to add more details to it or how to change to that movement mode in code. I’m making a variation of crouching, essentially, but slower and having your hitbox lower down, for crawling into tight spaces and such (think Metal Gear Solid.) Unfortunately, the only options I have in the custom movement mode are speed. I can’t control half height or anything like that. Does anyone know a way to do this? I was also unable to find anything saying how to change crouched half height in blueprint. If you can do either of those things, my problem is solved. Thanks!
-Your friendly neighborhood Squichee