How to change block size an dreplication factor in EMR with hadoop version 1.0.3

I am trying to change the block and replication factor to 64MB and 2.

I am using java SDk to create EMR clsuter. I add following bootstrap action:

    BootstrapActionConfig setBlockSize = bootStrapSetHadoopProperty("Set Block Size",
            "dfs.block.size=67108864");
    bootstrapActions.add(setBlockSize);
   BootstrapActionConfig setReplicationFactor =   bootStrapSetHadoopProperty("Set Replication Factor",
            "dfs.replication=2");
    bootstrapActions.add(setReplicationFactor);

But when when i check hdfs-site.xml file in master node the values for dfs.block.size and dfs.replication remins un-changed. Any idea on how to do this?