To disable the "placement challenged" Caps Lock key on the ITF keyboard,
use an xmodmap script:

Add the below lines to your ~/.dt/sessions/sessionetc:

/usr/bin/X11/xmodmap - <<'EoF'
  clear lock
  keycode 55 = Control_L
  keycode 86 = Caps_Lock
  keycode 39 = grave asciitilde guillemotleft guillemotright
  keycode 71 = Escape
  add Lock = Caps_Lock
  add Control = Control_L
EoF

This works until logout/login, when Caps Lock toggles the control feature,
even though 'xmodmap -pm' shows that Lock has no assignments.  You have to
restart the X server to reset completely, which can be automated by
uncommenting the line:

Dtlogin*terminateServer:   True

in the file {/usr,/etc}/dt/config/Xconfig.