As superman said you have to set up your Machine Definition with a 4th Axis and you have to have a post (.pst) that will handle it.
If you are going to do Index programming, I would really recommend getting used to or using the WCS Manager. I use it everyday for our Horizontals.
Mastercam's website has a little Tutorial about it. It is originally for V9, but works mostly the same for the X family.
http://www.mastercam.com/Support/Documentation/Files/WCS-ViewMgrTutorial.zip
Mike in MN
http://www.cncbasics.com
http://www.cncbasicsforum.com
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