As the other poster suggested, I would upgrade to get the presets for this. Then you have NTSC and PAL Anamorphic to choose from, no muss no fuss...
You can still do this in combustion 1.0 though, the new options are just presets to the existing capability. Just set all your footage and your composite to 1.20 pixel aspect ratio (NTSC anamorphic), and enable the "Use Aspect Ratio" option in the Window menu to see it in 16:9 aspect ratio.
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Greg Niles
combustion Product Specialist
Discreet