As most of modders dont know that Space Empires 5 has more capabilites for modding then previous games so i want you make to know that its possible!
This will be short...
Space Empires 5 is the most moddable game in Space Empires seriues/franchises...
So you can find about mods and tools at SEwiki and there are also many informations about other SE games, you can find all avalible modding tools and mods for Space Empires...
Just watchout,some mods support only older versions i think but who cares...
Heres the link:
I loved this game; Still do :)
Now you know how to mod...Probavly...
I am working on my own game with the UDK (Unreal Development Kit) so yeah i know how to mod. Plus i am taking some classes for making 3d models this year. :)