Wares plugin and logging.yml

I am running an instance of elasticsearch inside a jetty container,
using the excellent transport wares pluginhttps://github.com/elasticsearch/elasticsearch-transport-wares.
I pretty much followed the configuration that javanna uses in this github
project. https://github.com/javanna/elasticsearch-war-example

The only question I have, is that it seems like I need to use a
log4j.properties file directly for logging, instead of the (much nicer)
logging.yml format that elastic search allows. I'd like to use the
logging.yml format, but can't see a way to get it to work out of the box.

Any ideas? or am I stuck with log4j.properties?