I think this would epic if it is possible... Kinda got the idea from the Disco Sheep plugin... 1. Admin enters a command 2. Plugin gets a list of all creepers. 3. Plugin attaches a sheep to each creeper, and colors each randomly. 4. Plugin launches the "Shreepers" one by one and detonates them. 5. A rainbow of wool colors falls from the sky.
Hmmm what about using the animation for the Ghasts attack instead. That is working in 1.6 and looks like a flaming cannonball. Just shoot that into the air and have it drop colored wool upon explosion. Might even be able to have it be something that requires items like AimCannon.