In Brightest Day etc. etc.

[Ard3]

How about going the simplest possible way:
As Item of Power character has relevant aspect. Compel that charges run out when dramatically appropriate.
Similar to weapons needing reloading. No rebate but FP when it comes up.

[InFerrumVeritas]

We did a one off Justice League game using DFRPG rules last year.  Here's how I wrote up the ring:

Item of Power+1
Sponsored Magic (Oa, green light channeling, evothaum for conjuration, constructs, tracking, all focus items put into defensive enchanted items) -4
Modular Abilities (as many points as I could, minimum 1) -(x+2)
Stressful Change (custom power, on Modular Abilities, when changing abilities, take a point of mental stress for each refresh changed) +2

Total Cost -4 (minimum)

I handled recharging with compels, because in the stories it only comes up when the writer wants it to, which is what compels seem for (like how I handle reloading).

EDIT: It looks like a lot of this has been discussed, still this is the complete item I used.

I also gave an optional upgrade to stressful change (for -1) that made it a point of mental stress for every two refresh changed.  So it would only give a +1 rebate.  This required modular abilities with at least two form points.

NOTE: This is a bit of a stripped down version.  We were playing a 30 refresh game (the minimum I felt I could make Superman at), so I had a ton of powers just listed as given and a boatload of refinement for enchanted items.

[fantazero]

Fate Core it. Dresden is GREAT for Dresden, poor for Super Heroes.

But for Dresden
For Green Lantern.

Make PC take a Green Lantern Related Aspect (I answer to Oa, Guardian of Sector 6543, ect)
Make then Roll Will skill for using Ring based skills
Catch of "Yellow"
Stunts
Use Will instead of Guns when making Ring Based Gun Weapons
Flight
I mean everything else I would write up is basically Wizard stuff, like Rotes, Evocation, thamutrgy and all that. Maybe use the "Hunger" skill track as how much "Juice' the Ring uses? Roll Will Power to see if your Ring runs out of energy (ugh, this is where I hate comics, In Some versions of Green Lantern the Ring needs to be recharged every 24 hours, and then sometimes its based on how much energy the guy uses, and then in others its based on something stupider)

Thats the Problem with Green Lanterns, Superman, batman ect is they are really hard to Stat.

I have an idea where basically you use Story games to do Super Powered Games. Reskin "In a Wicked Age", or use "Prime Time Adventures", or Fiasco, where the "Powers" are a given but the Story elements are more important.

[InFerrumVeritas]

Fate Core it. Dresden is GREAT for Dresden, poor for Super Heroes.

Fate Core didn't exist when I played the game last year.  Not really.

[fantazero]

Fate Core didn't exist when I played the game last year.  Not really.

Time travel

[Sanctaphrax]

Never actually played DFRPG Supers, but I think it'd work pretty well.

I mean, I've had plenty of luck statting up superheroes outside of games.