With this mod you can harvest artificial parts & implants. Basically everything (non-natural) that can be 'added' to a colonist/prisoner with a medical operation: Prostetic Arms, Bionic Eyes, FancySpecialModAddedUberPart,...

To harvest those parts from a Corpse you need to build a Harvesting bench (requires at least 'Basic Harvesting' research). Here you can add 'Harvest corpse' jobs like any other recipe. More complicated parts need better research.

The harvesting recipes will only touch/use corpses up to the level of complexity of the job. Meaning a 'Harvest primitive' job will only use a corpse that contains (at most) Peg Legs (or similar), a 'Harvest advanced' job will touch corpses with Prostetics (or simpler), and a 'Harvest Glittertech' will touch any corpse.
If you are unsure, what level of harvesting you need for a corpse, click the 'I' symbol of the corpse in the bottom left. It will list a 'Max. Complexity' stat in the listing..
If you still can't harvest a part, make sure it's not too destroyed. The default settings for the mod allow reclaiming a part with 50% hitpoints (or more) in that part. If the part health is below that, it's considered non harvestable. That range can be changed in the settings.

Also - you cannot harvest from rotten corpses. So stock things in the freezer if you want to grab stuff.