I found a Gibson T-500 humbucker for 60 bucks, and my friend wanted it for his Ibanez Gio. Now, right there I should have seen the possibilities of what would go wrong, but I went ahead with it. I switched the Ibanez humubcker with the Gibson, and after a faulty soldering gun, no roll of extra solder, or adequete lighting, I got the pickup in.
It worked, although I managed to accidentally put the pickup selector in backwards.

Of course, the pickup was more than a Korean made starter guitar could take, so it sounded atrocious.
But it was fun.
So, I learned my lesson.
I hope one day I actually have the skills/money to build my own pickup, but....