That's exactly how I do it. In my demos, you'll usually see me get close to the gap (a little to the right, where when I press forward, I'm at the exact angle I need to be and move slightly left). Once I'm at that point, I grab the mouse and get to the pixel-perfect position I need to be at (if I'm going south, east, or north). West glides are so easy that I can just keep pressing the mouse forward and I'll go through automatically (unless when I set up, I managed to be too far to the left from the start). For west glides, the only thing I need to worry about is setting myself up and getting close enough to the gap without it being too slow (c410o201 is a bad example of this--I had a pretty slow setup. cc27o158 has better west glides). South, east, and north are a bit more annoying (especially east and north) because I don't automatically go through as I'm moving the mouse. I either have to move it really slowly to nearly guarantee getting through (which obviously takes too much time in a demo) or just hope I get lucky enough that my position lines up exactly with the gliding gap as I'm moving the mouse forward so I can go through. That's why c410o201 was so annoying--it featured an east glide that wasn't right at the beginning of the run/the only real thing I had to worry about going right. Take it from a natural keyboarder who learned how to do guideless glides really late in the game compared to other speedrunners, haha.
Thank you! I really appreciate that, though I must say there are a lot of speedrunners who have much greater skill than I.