Go to the wall, find a corner, knife it a few times. Keep you mouse as close to the corner as possible without slipping. Keep sprinting, if you run out of stamina, keep walking with mouse stead and sprint whenever you can. If you get partially in, try pointing a little farther from the corner. Remember: Anything is glitchable, depends if it is useful or not.
Use the search ban next timer, there are many tips and tricks.