For ships that move - add a unit as you did before only this time make sure it has a speed and is not docked
Now right click on the unit you added and select add waypoint
Now add your waypoints
Now you have a route
Click on the Play button top right
You can now watch your ship move along its route
Save as you did before and your .scr now looks like this
When you are happy with your new additions you can merge with the game .Scr
First make a copy of the Campign.Scr in case you dont like anything
With your own .SCR loaded in mission ed click file then merge it will then ask you for the other file you want to merge with - point it towards the Campaign.Scr
Tick the savable box and OK
Now you can save,,Click file\ Save scripted layer as Campaign.Scr
And overwrite the Campaign.scr that already exists
Now when you start your game your new additions will appear
Hope that of some help - I am not an expert and no doubt someone will come up with something better but its a start
