Sorry, not too clued up on the IS but I didn't think the rears on the IS used slide pins, I thought it was opposing pistons ala the good old days?
As far as the fronts go, when you say "rubbers", do you mean the rubber boots? The reason I ask, is one slide pin on each side has a rubber bush on it, so it could mean those. I did a turorial on the slide pins on my GS (the IS fronts are the same procedure), Clicky, so take a look on there to see what I mean.
p.s. The disc and caliper change tutorials in my sig lines are also the same procedures for the IS fronts.