First, use a scalpel to incise the skin about the calvarium. Remove and discard this excess skin. Using a chisel, or other jagged object, remove all overlying fascial and muscle layers in a similarly circumferential manner. Now it’s time to enjoy inhaling some human “bonedust.” Utilize a high-powered saw (note: contrary to popular belief, a scalpel is insufficient to get through bone) to cut through the skull in this ring, taking care not to cut too deep (or too shallow) – you’ll know when you’re in. Apply upward force on the calvarium while using a scalpel or chisel to free this bone from the adhesive dura of the brain.
Now you’ve got your brain. Incise the dura (preserving the falx cerebri and superior sagittal sinus, if desired) and reflect it to reveal the substance of the cerebrum. Removing the brain should be done with care. Use a scalpel to slice the cranial nerves, internal carotid artery, and pituitary stalk, as well as the vertebral arteries and spinal cord. The tentorium cerebelli should be cut in order to keep the brain intact upon removal. Lift the brain and the job is done.
Note that before any of these steps are followed, you should: A) ensure that your subject is dead, and B) either be officially licensed by the state to perform such a procedure, or be willing to be hunted by the law. Further information regarding the restoration of life to a disembodied brain may be found by combing the Internet.