[xmonad] Multiple statusbars

Hi Everybody, I am looking for a way to have two statusbars (xmobar or dzen), one at the top and the other one at the bottom of the screen, which could be always visible. I have tried some configs on the Xmonad/Config_archive and other from other sites, but actually I don't how to launch and set the second bar to be not hidden by the windows. Thanks for your help, Alexis. -- Alexis de BRUYN