1) Most hacks are detected on steam
2) Only steam can't ban you not anyone else so if people catch you and call you a hacker and report nothing happens.
3) If you're going to hack there is always a chance of being banned
4) VAC is Valve anti-cheat system it basically detects cheaters and permanently bans them.
The link you posted is a mod.
So yeah I have been hacking for 9 months in mw2 and I'm not banned and it's also worth noting that VAC in mw2 is not as bad as in mw3 and other cod games...