Re-Fraction

You Setup a normal Scavenge Script like always and setup everything you want.
Then under the ClickType you dont use LeftClick or RightClick or both, you "break" and "place" instead.

Here is an Example:

{
	"block_pools" :
	[
		{
			"name": "BreakNetherrack",
			"type":
			{
				"type": "block",
				"name": "minecraft:nether_brick"
			},
			"clicktype": "break",
			"properties":
			[
				{
					"type": "require_sneak"
				}
			],
			"drops":
			[
				{
					"name": "minecraft:iron_ingot"
				}
			],
			"messages":
			[
				{
					"id": "require_sneak",
					"message": "Player requires to sneak"
				}
			]
		}
	]
}

Now here a couple limitations: You can either use break or place or the other two options but never in combination.

That means when you decide to use break or place you can not use anything else in that Entry. LeftClick & RightClick and (Place if you used break and vice versa) can not be used. You need to setup a duplicated entry that handles the other parts. That is intentional.
On top of that you can not cancel a place/break action from minecrafts eventpool once its done its done. That is again intentional to prevent bugs.