What's the proper way to bond metallic signal wiring raceway?
You probably don't need to go full RMC; cheaper EMT and plain stamped handy-boxes will do.  Both types of conduit are acceptable as grounding paths for 200A++ of fault current, your milliamps of signal noise will be handled with ease.  I never run ground wires inside EMT.  

If you have a section of Conduit isolated from mains grounding, grounding it is simplicity itself.  There should be a hole in the back of the box tapped #10-32.  You simply put a 10-32 screw in there, shepherd's hook a 12AWG solid pigtail to it, and wirenut that to your grounding wire, any color you like as long as it's green, yellow/green or bare.

Then you exit the wire through a cable clamp or grommet, which fits in a standard knockout.  

Then you run the wire in-wall to whichever ground point you deem appropriate.  If you'd like guidance on that, look at the NEC rules for retrofitting ground.