What type of training and supervision is required for CAP members to marshall aircraft at an airshow?

CAP members may not direct parking of aircraft at air shows unless they have received training on aircraft marshalling and have a flight line authorization on CAPF 101 or CAPF 101T. A fully certified flight line marshaller (FLM) should be present to supervise all members in trainee status. 

In addition, from CAPR 900-5, the following rules must be followed.

b. Permitted Activities. CAP units and members may assist with an air show sponsored and conducted wholly by agencies and organizations other than CAP. Prior permission to assist or participate in any air show must be obtained from the General Counsel at National Headquarters. No such advance permission is required if the CAP assistance or participation in an air show is limited to the following:
(1) CAP members may be used as guides or to provide directions or information.
(2) CAP units may setup a recruiting booth and/or a concession stand selling food and drinks on the premises of an air show, providing that CAP is not in any way acting as a sponsor.
(3) CAP members may be used around parked or static display aircraft for guidance, information or direction.