Another option, although maybe not exactly what ur looking for...is to make the "kamikaze fighters" an ability for the ship(s) i.e. Carriers and Capital Ships. When activated it "summons" a bomber and sends it at the target. There may be a way to have it summon more than 1 and then have them form a formation somehow...it might end up being similar to the fighter squads, but it wouldn't be quite the same.
The summoned bomber would have the "kamikaze" ability that the advent guys have...and it would have to be set to autocast w/no cost or something of that nature, so that they could use it as soon as they're summoned and head for a target...or however the ability works, I honestly haven't looked at the mechanics of it.
The downside would be it would take up an ability slot on the ability pages of them to summon the "fighter" itself, although some of the capital ship abilities and whatnot are "weak" enough that they could be switched out without much noticing, lol.
The ship would probably end up being a "normal" ship, assuming you can't get the squad bit working - but you could make it so it doesn't take up any slots in the "supply".