I have made custom spawns along the main highway (the main road that goes around the map), on Chernarus. Pasted in at the bottom.

I don't know why you would use x, y, z coordinates for events - the events don't care about the y coordinate (the elevation) at all. They will simply spawn the event on the ground of your x and z coordinate. I don't think it is even possible to spawn an event on an elevation, let's say above ground, using the vanilla xml-file - you would need a mod for that. So it makes more sense to ask for coordinates like this (like all events are defined in vanilla cfgeventspawns.xml):

<event name="StaticTruckCrash">
<pos x="9188.72" z="13520.1" a="-1" />
<pos x="12562.8" z="14290.4" a="-1" />
<pos x="12825.6" z="9006.95" a="-1" />
<pos x="13071.6" z="7468.51" a="-1" />
<pos x="13386.5" z="5539.23" a="-1" />
<pos x="12425.4" z="3535.44" a="-1" />
<pos x="10983.9" z="2977.85" a="-1" />
<pos x="8475.69" z="2808.5" a="-1" />
<pos x="4165.1" z="2598.43" a="-1" />
<pos x="2272.77" z="2120.43" a="-1" />
<pos x="853.572" z="9929.49" a="-1" />
<pos x="1499.07" z="11117.3" a="-1" />
<pos x="4578.22" z="12993.1" a="-1" />
<pos x="5761.92" z="12637.5" a="-1" />
</event>