Aiight, here's a HL2:DM crosshair installer I;ve been using for years now. Its 100% safe, and made by the GoTG clan. Its easy, all you have to do is launch the exe choose your crosshair type and colour, then click install crosshair.
You'll hear exactly what its doing as it explains the process, and it shows the files it scans to find the HL2:DM folder.
Ez,
Rio
Source:
http://www.mishepsbasement.com/MiShepsCrosshair.htm

