If I was going to make hang gliding a regular part of the game world, I'd port in Pathfinder's 'Flying' skill and use that. I would persume that knowing 'how to fly' would apply directly to the experience of controlling a hangglider, and apply only a small circumstance penalty (-2 for example) on the first few checks controlling this new peice of equipment until you 'got the hang of it'.
If I was not going to make hang gliding a regular part of the game world, I'd probably ad hoc balance (to recover from difficulty) and tumble (to perform a maneuver) skill checks, and apply a circumstance penalty (say -5 initially, going down by for each successful flight long duration flight) if the flier had limited experience hang gliding.
Before you can design manuevers and such, you really need to design a system that explains what you can normally do in the air. Then you could make skill checks to perform normal manuevers (DC 10 and lower stuff), and advanced manuevers (DC 20 and higher stuff) that let you 'break the rules' in specific ways ('sharp turn', 'hover' or 'dive', for example). You are probably going to have to define what it means to be a flier and what it means to be a glider very specifically, and then define what it means to have particular manueverability classes. My assumption that having a particular manueverability class ('clumsy' or 'perfect', for example) would give you bonuses or penalties when performing Flying skill checks. For example, having perfect manueverability might mean you automatically succeed at a Flying skill check, where as 'clumsy' might mean a -5 on all such checks. Various classes in the middle would be somewhere between that.
