Wondering this myself, it's the last thing that needs to be done. I don't have a press and the local machine shop was worried about damaging the housing and doesn't want to do it.
As mentioned in thread and videos some mechanical apttitude is required for this. Not saying you dont have it but if your not sure on the process then its best to let someone who possesses the skills to do it to keep from ruining the $400 part.
Heres some tips....
First off if "Feet" on gear end of cam sensor are gone the sensor is not rebuildable.
Place the two bronze bushing in freezer to get cold...idea here is to have them contract is size slightly.
Take cam sensor completely apart....thats including the circular oil wick under reluctor cup.
Note the depth of old bushings in their bore as the new bushing will need to be in put in the same depth.
Clean housing inside and out with brake cleaner or, equiv to get the old residue out. If you are wanting to keep the GM part # legible on cam sensor neck then be careful when cleaning as some solvents will remove the numbers.
Place sensor body in a soft jawed vice.
BEING VERY CAREFUL NOT TO OVERHEAT Use a torch or heat gun (one with enough balls) and heat cam sensor body BEING VERY CAREFUL NOT TO OVERHEAT.
Once sensor is hot, CAREFULLY...repeat CAREFULLY drive out bushings (driving them toward the end closest to bushing) with a hammer and drift pin being careful not to gouge or damage bushing bores.
Inspect inside of cam sensor body for debris, damage, etc and clean if need be. If the housing is severely coked up with oil then a soak in a solvent will possibly be needed.
Now the new cold bushings can be pressed back in to the original depth as noted earlier.
Sometimes the lower bushing bore may be screwed up from front covers that the cam sensor hole is out of alignment, etc and the old bushing has been spinning and the bore wont accept a new bushing and retain it properly.
On a basic rebuild level if the above or the feet are worn off, the cam sensor main body would be considered non rebuildable without alot of extra work.