Taken from cheats for Far Cry 3, but also suitable for 2nd.
Start the game with the -GameProfile_IgnorePlayer 1 parameter
Example: “C: \ Program Files \ Far Cry 2 \ bin \ FarCry2.exe” -GameProfile_IgnorePlayer 1
Enemies behave like in neutral zones, but they cannot be pissed off.
If you run close to them, then they become more aggressive, take out weapons, but do not shoot.