Launching Firefox into “chromeless” mode from command prompt

Solution 1:

You could create a separate profile in Firefox for your "chromeless mode." To do that open the profile manager:

"\Program Files\Mozilla Firefox\firefox.exe" -ProfileManager

Create a new profile called "Chromeless"

Open the profile and hide the navigation and bookmark toolbars.
In the Options under Tabs make sure that "Always show the tab bar" is unchecked.
Install the Hide Menubar extension to hide the menu bar

Setup a shortcut to launch your new profile:

"\Program Files\Mozilla Firefox\firefox.exe" -no-remote -P Chromeless