Finding examples with AS2 to do a Remote Call (Fluorine or WebORB) is easy.
However, finding an example for AS3 is very, very hard.
Here's how you do it (thanks to Ward De Langhe):

PLAIN TEXT
Actionscript:
  1. private function getGalleryData():void{
  2.  
  3. registerClassAlias("logics.BLL.CollectionEntity",GalleryVO);
  4. registerClassAlias("logics.BLL.GridRowEntity",GalleryRowVO);
  5. registerClassAlias("logics.BLL.PictureEntity",GalleryImageVO);
  6.  
  7. galleryService=new NetConnection();
  8. galleryService.objectEncoding=ObjectEncoding.AMF0;
  9. galleryService.connect(SiteModel.GATEWAY_URL);
  10. //SiteModel.GATEWAY_URL is url path to your gateway
  11. responder=new Responder(galleryResult, galleryFault);
  12. galleryService.call("remoting.service.CollectionService.GetCollection",responder);
  13. }
  14.  
  15. private function galleryResult(result:Object):void{
  16. galleryVO=result as GalleryVO;
  17. }
  18.  
  19. private function galleryFault(fault:Object):void{
  20. }

We haven't been able to figure aout why ObjectEncoding.AMF3 doesn't work.
Well, it works, but in the result the objects are not deserialized, so you just get Objects...