Hi again,
No, the S-1 switch is not the same as a three way switch... I'm sure you can use a three way, or a five way for sure, to function as an S-1 switch, but that would for sure kill the versatility the S-1 switch is meant to give.
On a Tele, the three way switch gives you the option of running each of the pickups alone or in parallell... The S-1 switch gives you the option of running them in series instead. So you get a fatter tone out of your pickups.
This works great with singlecoils, but what if I've never heard that with combining with humbucker or P90's... or any other combination with those for that matter.
http://www.premierguitar.com/articles/M ... ing_System