I'm not affiliated with Bay 13 but those bolts are very reusable and although I'm sure there are torque specs for them, it's really not critical, just "tight" works for me.
Now, if you've removed the pan and using the OEM Volvo sealant, letting it dry overnight before adding oil (at least that's what I do), there's no way it should leak. If you're having a problem with just one or more bolts showing signs of seapage from the threads, then the cure is to remove that bolt, use brakeclean to degrease the threaded areas and let dry, then apply sealant to the bolts threads. Silicone sealant works well for that job.