So, there is two different starts to make a new ability:
1. You know that there is a very similar existing ability (Scramble Bombers) to what you want, so you check it out, on which ship is it in the game, after that you open that ship's or module's entity file and find that ability. Now you know the code name of it (AbilitySpawnSquad).
2. You don't know a similar ability so you go to the Bailknight's post (https://forums.sinsofasolarempire.com/306405) and you check the buffs, maybe there is a command for what you need, and that's how I find the CreateSquad comand. After you know the command you need an example, so you don't freeze the game with a wrong ability. Run the 'Windows Grep', this program can search in files. And after that I find the AbilitySpawnSquad.entity.
In this case this ability is almost perfect, the only bad in it the lifetime limit (expiryTime) of the squadrons. You have to reset it. I think you want no time limit, so modify the values to '-1.000000' what represents the infinite.
Sorry for my first (really short) reply, but after this you can make new ability with such a few info I hope 
