I've heard conflicting answers regarding this so i'll ask it here,

I'm installing prothane bushing into my 4 links

When re-installing all the 4 links, is there any special procedure you have to do?

I've heard some people mentioning about setting preload and also that the bolts should be snugged up when the diff isn't drooping, ALSO i've heard it doesnt matter at all and to just slampem in.

So which is it :S

If your supose to set "preload"... how?

To preload you just tighten the bolts holding the links with the links pushed all the way up. This only works with stock bushings... It just makes the car sit a tiny bit lower, but doesn't really do anything besides that. Just install it however it's easiest for you and don't wory about it

It is best to tighten the bolts with the full weight of the car on its wheels.
The bushing can get trapped when the bolts are tightened and then it has to rotate in its housing when the suspension moves up / down.
If it is close to its centre point when the bolts are tightened the rotation amount is minimised.

^That.

It's best to follow the procedure in the service manual, link: http://www.hachiroku.net/downloads/AE86Manual.pdf

...basically tighten the 4 link bolts with your hand so they're snug, lower car to ground, bounce the rear of the car to settle suspension, jack up rear of car by diff. leaving the suspension loaded, and tighten the 4 link bolts to spec.

Setting pre-load is only necessary for rubber bushings because they are glued in place. Once you go urethane, they spin freely and it doesn't matter.