States 30 - 35 Nm as I read it here (although that seems a bit odd). But have a look yourself, part 3AZ on the torque list, same as front guide bolts.
http://tis.spaghetticoder.org/s/view.pl?1/04/54/71
It also list it here as part 5AZ in with the rest of the specs for the rear caliper, again just the same.
http://tis.spaghetticoder.org/s/view.pl?2/51/53