Personally I don't see a reason to do it. Wasteland is Wasteland. Why would you want people to always be aware of enemies near them. It kind of takes the point of Wasteland away.
Anyways, if you wanted to do so, you could use client\functions\createGunStoreMarkers.sqf
to get you started. Assign it to attach to an object, remove the map marker and presto. Wouldn't be too hard.