Run Soap UI prompt from command prompt

From the picture you posted i can see that you are creating the dialog yourself from a Groovy script to toggle environments yourself, which is fine. What i would do if i wanted to run the script in a headless environment is to first wrap the

UISupport.showPopup(...)

With a isHeadless() test. 

def environment = '';
if(UISupport.isHeadless()){
    def environment = project.getPropertyValue("my.environment.prop") ?: "defaultEnvironment" 
}else{
    UISupport.showPopup(...) //select environment in gui
}

And specify the environment right at the commandline using -Pmy.environment.prop=devLocal

Does that help?