Hex editors

[Notrel]

So I've been asked by a friend to try and break their game so that they can figure out ways to prevent it from being broken upon release.

The question I have for you is - will the use of programs such as hex editors be detected by the VAC system?
I have no intention of using it on any games other than the one I've been asked to "stress test" (which has nothing to do with Steam) but I want to make sure it won't trip a false positive in the VAC system before I install it.

[Snaggle]

It won't cause a ban, you'll be fine.

[Notrel]

Thanks, wasn't sure how VAC works, I'm just good at finding "unintentional game mechanics"

[EDIT] To clarify, as a kind of example... "If I have this item in this place and do this thing, then that thing will break and the rest of the game will be unplayable."
The hex editor is so that I don't have to go through the trouble of finding "this item" before testing things I think might break the game. I can just change a few numbers and the item's in my inventory.

[Zekiran]

If you're doing anything with a Vac-enabled game, do so at your own risk, it doesn't matter how otherwise 'safe' the program might be in a non-vac game.