clio would have a few annoying side quests that unlock the customization for your airship. once the ships are unlocked, her quests would be available in the same city you got your ship and usually involve some sort of race or supply mission with a timer. once the specific custom option is unlocked; you'd have to get specific items from random drops in order to make the customization you're wanting. failed missions and she gives you snarky comments, success an she's begrudgingly complement your skills. customization takes between half to a full day in game to complete. there's also a secret side quest unlockable through erik's side quests when done correctly that will allow you to add clio into your party.
too sexy to keep unhidden