As the previous poster said (kind of), it's possible to save some money and replace the bearings only, rather than the entire pulley assembly, if you want to go through the trouble. If you're going to do them all at once, maybe it's worthwhile. Search the forum to find the specs for the bearings.
If you're asking which way the pulley bolts turn, it's obvious you could benefit a lot by investing in a Bentley shop manual. As you work more on your car you'll find out that everything has a torque specification, and this manual's got them all. Save time on one job and it's paid for itself. THE BEST money you'll spend on your car. This is the best price I've found:
http://www.amazon.com/Porsche-Boxster-Service-Manual-1997-2004/dp/0837613337
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