There's about just as many ways to do Engineers as there are folks around. If you want to grind him, you'll have to grind materials (don't know which ones, as he doesn't sound like an Engineer I've met) and let him do modifications on your ship. And since I don't like grinding, at least not for long (one reason why I have two accounts, and have to forcibly restrain myself from buying a third), that's not the way I'd do it.