Philip Cord has kindly sent me this code that allows to create annotations with the "Author" tool property (older versions than CS3 couldn't get this on script listener - only on the CS3 script listener).
Hope it helps anyone like me that can't have access anymore to CS3
var colour = new SolidColor(); colour.rgb.hexValue = 'ff00ff'; selectNote(0); colourNote(colour); addAuthorToNote("Author Name"); function colourNote(colour) { var Saturation = colour.hsb.saturation; var Brightness = colour.hsb.brightness; var Hue =colour.hsb.hue; var desc = new ActionDescriptor(); var ref = new ActionReference(); ref.putEnumerated( stringIDToTypeID('annotation'), charIDToTypeID('Ordn'), charIDToTypeID('Trgt') ); desc.putReference( charIDToTypeID('null'), ref ); var desc2 = new ActionDescriptor(); var desc3 = new ActionDescriptor(); desc3.putUnitDouble( charIDToTypeID('H '), charIDToTypeID('#Ang'), Hue ); desc3.putDouble( charIDToTypeID('Strt'), Saturation ); desc3.putDouble( charIDToTypeID('Brgh'), Brightness); desc2.putObject( charIDToTypeID('Clr '), charIDToTypeID('HSBC'), desc3 ); desc.putObject( charIDToTypeID('T '), stringIDToTypeID('annotation'), desc2 ); executeAction( charIDToTypeID('setd'), desc, DialogModes.NO ); }; function selectNote(number) { var desc = new ActionDescriptor(); var ref = new ActionReference(); ref.putIndex( stringIDToTypeID('annotation'), number ); desc.putReference( charIDToTypeID('null'), ref ); try{ executeAction( charIDToTypeID('Shw '), desc, DialogModes.NO ); }catch(e){} }; function addAuthorToNote(Author) { var desc = new ActionDescriptor(); var ref = new ActionReference(); ref.putEnumerated( stringIDToTypeID('annotation'), charIDToTypeID('Ordn'), charIDToTypeID('Trgt') ); desc.putReference( charIDToTypeID('null'), ref ); var desc2 = new ActionDescriptor(); desc2.putString( charIDToTypeID('Athr'), Author); desc.putObject( charIDToTypeID('T '), stringIDToTypeID('annotation'), desc2 ); executeAction( charIDToTypeID('setd'), desc, DialogModes.NO ); }; function makeAnnotation(X,Y,Width,Height) { var desc = new ActionDescriptor(); var ref = new ActionReference(); ref.putClass( stringIDToTypeID('annotation') ); desc.putReference( charIDToTypeID('null'), ref ); var desc2 = new ActionDescriptor(); var desc3 = new ActionDescriptor(); desc3.putUnitDouble( charIDToTypeID('Hrzn'), charIDToTypeID('#Pxl'), X ); desc3.putUnitDouble( charIDToTypeID('Vrtc'), charIDToTypeID('#Pxl'), Y ); desc2.putObject( charIDToTypeID('Lctn'), charIDToTypeID('Pnt '), desc3 ); var desc4 = new ActionDescriptor(); desc4.putUnitDouble( charIDToTypeID('Hrzn'), charIDToTypeID('#Pxl'), Width ); desc4.putUnitDouble( charIDToTypeID('Vrtc'), charIDToTypeID('#Pxl'), Height ); desc2.putObject( charIDToTypeID('Sz '), charIDToTypeID('Ofst'), desc4 ); desc2.putEnumerated( stringIDToTypeID('annotType'), stringIDToTypeID('annotType'), stringIDToTypeID('annotText') ); desc.putObject( charIDToTypeID('Usng'), stringIDToTypeID('annotation'), desc2 ); executeAction( charIDToTypeID('Mk '), desc, DialogModes.NO ); };