Ia ma afraid currently this is not supported, but I found a sample workaround. You can find it in the attached archive. Please note it does not work in IE browser.
However our developers are working on RadTreeList improvement and in the next version 2014 Q3, it will support elastic behavior. Also the vertical alignment will be build in.
I hope this helps.
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.