The wheels are "hub-centered", meaning that the weight is primarily carried by the hub, not the bolts. As a result, you can ease off and then retighten bolts without having the car jacked - I don't mean bolts being backed way off, just eased slightly so that they are less tight than the torque spec, so that they tighten slighty with the torque wrench. I back off all of them first, then torque them with a click-stop torque wrench using a criss-cross pattern so that the stress is kept balanced across the rotor. You have to look up teh correct torque for the car, as not all Volvo's are the same. I believe the 850's are all 81 foot pounds, but that's just from memory. The rear wheel drives are all lower specs, about 65. I use anti-seize, but carefully. You do not want any of it to get on the bolt "seats", just on the threaded shank, so that it doesn't distort the torque readings too much. That's how I do it, at least, and its been trouble free and warped-rotor free for me for over a million Volvo miles so far
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Mike Sullivan ('91 745 (171k), '93 965 (147k), '95 855T (60k), '98 V70XC (78k). Past Volvo's: '85 744 (256k), '86 245 (165k), '86 245 (195k), '88 745 (208k).