I was wondering how can I script when in mouse look you hold down the left click button for certain amount of seconds it does a specific action
It's not that hard, but there's a lot of boilerplate code needed to get mouselook touches reliably. Here's some code of mine which does that. This is a little wearable object which lets you click on things in mouselook and read their pathfinding properties. You can adapt that to do other things. Enjoy.