It used to be you had to edit the server.xml to add a context path. now it seems that Pallada picks up on Catalina/localhost/xxx.xml files based on the context you're calling in the tomcat settings.
To try it:
setup a web app run setting with /myapp in the context, although this path does not exit in server.xml and won't show up in the drop down, you can still type in anything you want.
then go to <tomcat-root>/conf/Catalina/localhost and copy manager.xml to myapp.xml and edit it. I would remove the docBase, turn on debugging.
Now run your app in idea.
JB, is this intended to work, or did I discover this by sheer luck?