http://volvospeed.com/bay13.htm has the step by
step procedure including torque specs for the various
parts that are removed and replaced.

The rotors actually "float" and the lug bolts hold them on.
(One small 10mm bolt keeps it from falling off, along with
some rust.) Speaking of rust, my old rotors were so rusted
on I had to use an 8lb sledge to break them off (after first
trying 3 smaller hammmers). (And yes, the 10mm bolt was off.)

The bolts you need to torque are for the caliper bracket
and the caliper bolts to the bracket. OEM rotors come
with new bolts for the caliper bracket pre-coated with
loc-tite (or equivalent). You might want to use some if
re-using the old bolts.