This is not possible at the moment.
We had difficulties trying to get the one defined by the browser as well.
As we go towards having all logs and audit to UTC in 4.2 the latest, for log aggregation purposes, we might not invest time in that as well.

However, perhaps it can be easy to set this up in the ui plug-in definition. It will require manually editing the file, but it is a valid workaround.

Scott / Vojtech, your thoughts?

Thanks,
Oved