Conversion of milling machine to 3-axis cnc with optical encoders

I just joined this group and would like to convert my 3 axis milling
machine to a cnc with linear code plates for each direction. I have
heard about Mitutoyo's Millstar as apossibility. Does anyone have
any experience with this or other pacjkages.

I also have a cnc router that is programmed using mastercam to
generate the G-code. Is Mastercam usable for 3-axis conversion
systems?

Thanks for any help.

JoeM