This is a new particle mod made by me. I copied many parts of this explosion from the BTTF Part II Movie itself. You can see it in this video. Please excuse my driving and the lag.
I am only releasing the explosions because everything else didn't originate from me. The wormhole was part of a snapshot of Carlos McFly's BTTF: The Game Wormhole Animations video and the fire trails were part of another mod posted by DMC88ELB.
Here's the old download: http://goo.gl/ucLMD
The directions are in a text file in the download.
Good Luck!
-BTTFModMachine