Just like @dark_wood said. Also the video from SUNTSAG is exactly the one I used. Also you can rearm without installing the mod these days, just make sure a transport vehicle is in range of the scud and built it in open Beta ME
They can be reloaded by placing the Scud launcher within range of of one of Ural-375 trucks (I used Mobile C2 version). Just be aware that it takes a looooooong time .
There is a mod out that makes the re-arming truck more realistic