(a) If the court is satisfied that the defendant is an incapacitated person and the defendant is not in custody, the court shall cause the defendant to appear before it at the time of issuing a final order of observation, temporary order of observation or order of commitment, or other appropriate order, as the case may be.

(b) The court shall forward to the Commissioner of Mental Health the order committing the defendant to his custody together with a copy of the examination reports, a copy of the accusatory instrument and, if available, a copy of the presentence report. Upon receipt thereof, the Commissioner of Mental Health shall designate the institution in which the defendant is to be placed and give notice of such designation to the sheriff or local correction department, as the case may be, who shall deliver the defendant, if in custody, to the person in charge of the designated institution, except that, in the case of final orders of observation, the Department of Mental Hygiene may provide the transportation to the designated institution.