A wearable cape with the jetpack effect
Maybe include a logo on the cape
Leave flight animations as is for comic effect (not that there are any animations for flight anyway)
also maybe have a audio track playing when wearing the cape or just for using the flight ability when the cape is equipped
have the ability to customize various attributes like lining and the colour etc.
Personally, I only see this idea as a daft mod as the lack of flight animations would detract from any seriousness intended.