Custom needle ( normally ) it depends on the form factor, but that will likely be it.
It could also be done with a scalpel to make the incision, and then another tool to make the cavity, the implant is then inserted, and closed up with a stitch or two, or possibly an adhesive.
It all comes down to what the installer is comfortable with and what they can legally do.
Here are a couple of videos that should answer your questions