Clustering has changed between versions 5.6 and 6.0. Instead of clusters, 6.0 supports the idea of a policy group, where all policy servers in the policy group share the same policy. While it may be possible to implement central logging in 6.0, it's not really how policy groups have been designed to work, where each of the individual policy servers contribute to the group as a whole.
We would recommend disabling central logging for both event and iologs and allow the primary and secondary policy servers to store their own logs locally. Privilege Manager 6.0 allows you to search log files across all the policy servers in the policy group running the pmlogsearch command on the primary policy server. Having the log files on multiple policy servers allows pmlogsearch to run a faster parallel search across multiple servers simultaneously instead of searching one huge event file located on a central server.