You might check out the Titan Icon project, which opens up the Costume Maker and lets you play CoH Paper Dolls design characters with it.
Of course, some might find it too frustrating to be able to create characters visually, but not play them. But others might not.
Note that directly working with the CoH files may violate the CoH Terms of Service (ha!) or cause someone at NCSoft to become quite cross with you (HA!).
(h/t to ZzzzSleep)