How to configure not active theme

Dear all,

When using device theme switcher plugin, two themes are collaborating:
1. the active theme for the “standard” version of the website
2. another theme for the “device dependant” version

My question is: “how to configure the second not active theme device dependant ?”

Thanks in advance for your help,
Lionel

http://wordpress.org/extend/plugins/device-theme-switcher/