Create core with user-defined the instanceDir

Hi All

With the Solr-4.4 ,I try the Hdfs and SolrCloud.
I create a SolrCloud core with hdfs using :

http://10.7.23.125:8080/solr/admin/cores?action=CREATE&name=testcore8_1&shard=shard13&collection.configName=myconf&schema=schema.xml&config=solrconfig3.xml&collection=collection1&dataDir=/soData/

Checking the Hdfs ,I find the created path：
drwxr-xr-x - hadoop supergroup 0 2013-08-20 18:05
/solrdata/collection1/core_node16
drwxr-xr-x - hadoop supergroup 0 2013-08-20 18:05
/solrdata/collection1/core_node16/soData
drwxr-xr-x - hadoop supergroup 0 2013-08-20 18:07
/solrdata/collection1/core_node16/soData/index

Can i define the instanceDir by myself ,rather than using the default
instanceDir?

Also I have try the command:
http://10.7.23.125:8080/solr/admin/cores?action=CREATE&name=testcore8_1&shard=shard13&collection.configName=myconf&schema=schema.xml&config=solrconfig3.xml&collection=collection1&dataDir=/soData/&
instanceDir=heihei
However, It does not work...

Regards

Thankyou