This assumes that you are running ROX-Session.

There are three different methods you can use:

1. Click on the window manager you want in a ROX-Filer window. For example, you could click on OroboROX to switch to that.
2. If you don't have a wrapper for your window manager (and you don't want to make one),
   just quit your current window manager and ROX-Session will ask you to type in the name of a window manager to use. If your window manager doesn't have a quit feature, you can kill it using System or a similar process monitor.
3. This command can be used (either directly, or in a wrapper) to send a message to ROX-Session telling it to change window manager. Replace xfwm4 with the desired window manager (which can also be a full pathname):
   

   dbus-send --print-reply --type=method_call --dest=net.sf.rox.Session \
     /Settings net.sf.rox.Session.Settings.SetString string:ROX/WindowManager string:xfwm4