I assume you know how to orb walk in the first place? It's not just clicking attack-move somewhere/on someone, and more than that you can even do it without ever actually using a-move.
Which is to say to orb walk, you input a command to attack someone, then before your AA completes (but after the projectile leaves [neglecting the fact that technically melees can orb walk too]) you input a normal move command in whatever direction you want to go in order to cancel the animation involved in the tail end of your AA, then after you've walked a few steps (give or take depending on AS) you input another command to attack the person, and you repeat that process.
It's quite mechanically intensive, and if you have a high ping it probably wouldn't work very well to even try, but the individual pieces are all straightforward, and if any of them aren't working (i.e. move commands aren't registering while you AA someone, or you can't AA people at all) then that suggests a bigger problem since the game would be more or less unplayable if those things didn't work.
