You might want to check out this archived webinar
It explains the features of asyncronous replication from cluster to
cluster or cluster to myISAM. One of the reasons is exactly what you
want. HA via cluster for most of it and replicated myISAM for data
analysis. There was also somewhere a post before showing all the steps
very clearly to get you up and running for testing with this very
configuration. I'll see if I can find it.