Medronio,
Can i simply unscrew the saddles and change them directly?
It depends on which TOM model you have, hence : how are mounted the screws of the saddles.
For example, I have done that swapping job on one of my Tune-O-Matic (Gotoh-made, I believe) where the screws where retained in place via "E/truarc" steel rings. I first removed gently these rings with a scriber, being careful that they would not jump in the air because these are springs, then unscrewed the screws, then removed the saddles and re-arranged them, and reassembled the whole.
Have a look to my BIGSBY Tutorial in the sticky posts : there is some pics and infos about that.
A+!