I use X3, but I can give it a shot and try to walk you through it if you can't find any other support.
Start trying all of the available Machine Definitions and Control Definitions and Post Processors you have and find the one that outputs G-code closest to what is needed.
Then make copies of that Machine Definition, Control Definition, and Post Processor and rename them MULTICAM 3000 ROUTER, keeping the appropriate extensions.
Open MasterCAM and under Settings, open the Machine Definition Manager. Select Machine Type to Open - Router. Then open your newly created router, MULTICAM 3000 ROUTER.rmd. Change the control definition to your newly created control, MULTICAM 3000 ROUTER.control. Open the Control Definition dialog and change the post to your newly created MULTICAM 3000 ROUTER.pst.
Once you complete these steps, message back and I will try to walk you through editing the post processor to change the G-code that is output as needed.