post.jar with security.json

[Oakley, Craig (NIH/NLM/NCBI) [C]]

In the old jetty-based implementation of Basic Authentication, one could use 
post.jar by running something like

java -Durl="http://user:pswd@host:8983/solr/corename/update"; 
-Dtype=application/xml -jar post.jar example.xml

By what mechanism does one pass in the user name and password to post.jar (or, 
I suppose more likely, to solr-5.4.0/bin/post) when using security.json?

Thanks