If you can find the episode of Simpsons where the Salem Witch Trials
are re-enacted I before Sunday of this week (9th of January) I will
give a ten dollar tip.  This may be the third segment of Treehouse of
Horror VIII "Easy Bake Coven" but I'm not certain.  I think there is
another one that has more in common with the Salem Witch Trials.  If
you are certain that the episode MUST be only "Easy Bake Coven" then
please send me a script proving that it is the episode I am looking
for.  Again, I am looking for any place to buy (or download) this
episode.  Thank you.

I think "Easy Bake Coven," from "Treehouse of Horror VIII," is the right episode.

"Easy Bake Coven is set during the Salem Witch Trials, and sees the
Bouvier family terrorising the neighbourhood."

http://www.bbc.co.uk/cult/simpsons/episodeguide/season9/page4.shtml

"We'll stick with the family and take a look at Witch Marge. She
appeared in THOH VIII's 'Easy-Bake Coven,' which poked fun at such
varied sources as Hocus Pocus and 'The Crucible.' Exploring the
origins of Halloween, we're taken back to early Salem just in time to
see Marge outed as a witch."

http://www.oafe.net/yo/wosthoh3.php

Unless you go to P2P sources, I doubt that you'll find this episode
for download. Fox has thoroughly policed the Web for copyright
violations, and most sites that used to have Simpsons scripts and
video clips have taken them down because of the threat of prosecution.