Right now, the collections API isn't self contained - to do server administration, you still have to externally use the zkCli.sh scripts to upload configs.
It would be really nice to be able to issue a collections API call to upload a configuration and link that config. I realize that this providing a direct layer into Zk, but the benefit is that at that point - Zk could be completely hidden and behind the scenes - and only exposed to Solr itself.
I would suggest that it take a file upload, examples:
You could even extend the CREATE operation/api to take configContent and configContentType file upload, and dynamically create a configName. Then creating a collection becomes a one-shot API call with no outside dependencies.
I would suggest that the zip/tar content be specified as rooted at the based of the config dir.