you cant make a unit put there hands up to my knowlege but you can make them put there hand behinfd there head
wich is
unit_name playmove "FXStandSurUniv"
that will put there hands behinfd there head
and to make them sit down is
unit_name playmove "Effectstandsitdown"
that will make them sit on the floor if you want them to sit n a chair it is
unit_name playmove "OnChair"
and all those go in a waypoint or in an init field or script or what ever you want
but some may need the unit to be in a specific stance like to make them sit they must be in safe mode