Here are some useful torques I saved when I was changing the alternator and tensioner:
Torques (N52 Engine)
* Idler pulley to alternator housing - 80 Nm (59 ft-lb)
* Alternator to engine block (aluminum bolts, replace with new) - Stage 1(10Nm) Stage 2(an additional 180deg)
* Belt tensioner torque 25Nm + 90 degrees