Don't think it will have to be done on CNC. If you are just wanting to remove a section of the cover more than one way to skin that cat, Jig Saw, Cut-Off Saw, Drill and File, Mill done manually, probably more too. As to engraving what is already there any one who does engraving can handle this. Look at GunSmith, Jeweler that sort of thing. Aluminum even cast aluminum would be way more easy for some of these guys to engrave as it is so soft.

RS