What Ernie says! Because the node will be joining an already-running cluster, the main.cf file won't be read. If you are using 5.0, I'm not sure if it'll be overwritten by the new auto-save-type option.
If you wanted to force the edited main.cf to be read, then you would need to stop the cluster (hastop -all -force), then hastart on the edited node first, then start the other nodes. You could also start the other nodes in the stale state (hastart -stale (IIRC)), then startup order wouldn't matter.
All of this is from memory, so may not be right ;)