i've found a way to make it happen basically every single time
if you do moveforward(0.1); and then spam movebackward(0.2);schedule(66, 0, movebackward 0); in console about every tenth of a second (sometimes you have to be crouching) you eventually start going through the wall
it's almost like the collision is checked using a tick-like system and when you're moving slow enough and you're lucky with the timing you can make it through any wall
i haven't tested this on badspot's server yet but i think it would definitely work on there too