I normally use Terminal.app as my default shell application on my Mac. I always forgot to turn on X11 terminal before Chimera. I found a way to overcome the "problem", typing:

$ open-x11 chimera
if Chimera application is in your path, should automatically open a X11 sesion and Chimera

Other option is to create an alias in your bash or tcsh profile such us:
bash:
alias chimera='open-x11 /Applications/Chimera.app/Contents/MacOS/chimera'
or tcsh:
alias chimera='open-x11 /Applications/Chimera.app/Contents/MacOS/chimera'