I have heard of megaship scenarios before but not actively looked into them much as been happy with my EZ’s. With that said, I’m always up for experiencing different instance challenges which are engaging.
They are fun. The easiest type to get used to are defend against pirates, so you side with the owner. (always the controlling faction for the system). They will last about ten minutes or so, and you get 3 waves of pirates come attack you and either try to rob the megaship or damage it. Choose a high security system first time as they can get a bit hairy even if you're experienced otherwise.
The main trick I've found to getting them to spawn is to have the controlling faction in boom, but there are various other states that work too. This rule is about 90%+, but jump out and back in if one doesn't spawn.
So you drop on one like any station. Fly around and crash into it a bit, or just behave like a teenager on a skateboard and the pirates will arrive - I say this because otherwise you can sit there playing with your winky for a few minutes otherwise. But right conditions, and those devils will come.
Once they arrive, you get to pick a side like with a CZ. So pick defend to begin with. Different types of megaships will spawn more pirates too - I get the best with haulers, but they are all good normally, prison ships aside.
Kill everything that shoots at you. Be careful of hitting the megaship, as it gets cranky, and often the cops go nuts for no reason too (don't hold me responsible for any hilarious accidents!).
After 3 waves it ends and you can go out and back in, again like a CZ. The big money ships are the deadly condas and pythons and they normally do the hatchbreaking, so can be like fish in a barrel. Bearing in mind you might get up to 20 ships taking a fancy to you!
On average, at a hauler in boom, I can probably get 7-10m just for the controlling faction in a ten minute scenario. Kws for an extra 30%. Sometimes a bit more, rarely less.
Let me know if I've missed anything out, or pm me sometime in the week to wing up. I hope you enjoy them though, I think they are excellent fun, especially in wing, and really are a totally different thing to res hunting.
Have fun mate!