Sit in your preferred posture (hand over hand is recommended) and close your eyes. The idea is to remove external stimuli or at least minimize it.
Have strong determination. Set an intention to not "itch the itch" or get up.
Point your concentration toward your body.
Slowly scan from the top of your head to tips of your toes.
If sensation arises, witness it with neutrality.
Watch it change over time.
If Mind wonders, then sit your mind.
Continue to slowly scan your body (This could take 1hr for 1 direction).
Notice the sensations arising, passing and changing. Be neutral.
Don't force sensation, neutrally witness if there is sensation.
If no sensation, subtle or gross, move on to the next part of your body.
Slowly scan your body, part by part, from the tips of your toes to the top of your head.
Self-evaluation of depth:
Concentration strong and neutrality predominant for 1hr+?
Proceed to