The MX series use G400 to apply tool offset to the tilting head.
There is a programming manual that describes this quite well (MXTTPGE68). I'm unable to upload the .pdf file to this site, so if you'll PM me your email address, I'll send you a copy.
As far as the installed options, short of contacting the dealer or Doosan, I don't know of a way to tell what you have. I don't imagine you have the option you described, however.