How do I wrap cables around AT-ATs with the Snowspeeder?

I'm having trouble figuring out exactly how the Snowspeeder mechanics work — specifically cabling AT-ATs — because they're always quickly shot down by TIE Fighters.

On PC, what do you have to do (both in-game and keypresses) to cable an AT-AT? Do you need to hold or press the button(s)? And is this possible to do right when you start flying the Snowspeeder or do you have to wait for something?

By default, you have to press 4 (PC) or Y (Xbox) ∆ (PS) (this is the special action key, the same used to activate the speeder powerup) as you fly past the AT-AT.

After that, it will bring up a form of quicktime event, where you have to push the mouse/control stick up or down to "keep the speeder stable". Visually, this is depicted with a bar that shows whether you need to push up or down more. If you do this for long enough, the AT-AT will be destroyed.

Note: you can only do this during a Y-Wing run, when the shields on the AT-ATs are disabled.

UPDATE: Your stability is also affected by how much your speeder is attacked while you are cabling the AT-AT; too much fire from the enemy will destabilize you and possibly cause the cabling to fail. (thanks @Mufasa for this)