From: Alexander Ameye
hey man,
I was using the 'SetPivot' script written by Yilmaz Kiymaz and then I saw
that you uploaded an edited version. I was wondering, in what way is this
script different than the original, and also, does this script fix the
issue when you try to change the pivot point of rotated objects? much
thanks!!
wow, I've made that script over 4 years ago. I can't believe it's still relevant for something today! I'd hope Unity team would have brought a better solution there by now.
too bad I can't remember why I've made it and I didn't document it enough there. I don't think it fixed any of the original issues, though. also I was toying with unity up to late 2014 and since this was last updated in 2012 I probably didn't use it much. dammit, I wished I could remember exactly why that exists...
I do remember I was trying to understand how SetPivot worked, reason why I keep saying it's a simplified version. probably eventually I figured a better way to handle the pivot issue though. so sorry I won't be able to dig deeper into this any time soon! but I'd love to learn more about your quest once you figure it out. 
Haha yes, the default solution given by unity is still to create a parent object that functions as a pivot point, but in my case that takes a lot of code.. Just changing the pivot point would be much more efficient. Currently I'm also figuring the original script out and modifying it to fit my needs. If I get it integrated enough into my script and polished enough, I'll send you a link of my asset! Thanks bud