[Delphi] Changing Printer Paper Size

var
    Device, Driver, Port: array[0..80] of Char;
    DevMode: THandle;
    pDevmode: PDeviceMode;
...
...
    // Get printer device name etc.
    Printer.GetPrinter(Device, Driver, Port, DevMode);
    // force reload of DEVMODE
    Printer.SetPrinter(Device, Driver, Port, 0) ;
    // get DEVMODE handle
    Printer.GetPrinter(Device, Driver, Port, DevMode);
    If Devmode <> 0 Then Begin
      // lock it to get pointer to DEVMODE record
      pDevMode := GlobalLock( Devmode );
      If pDevmode <> Nil Then
      try
        With pDevmode^ Do Begin
          // modify paper size
          DEBUG('Old dmPapersize = ' + IntToStr(dmPapersize) );

          if Unit2.ActiveAccount.clPaperSize = 0 then // Letter
            dmPaperSize := DMPAPER_LETTER
          else
            dmPapersize := DMPAPER_A4;

          DEBUG('New dmPapersize = ' + IntToStr(dmPapersize) );
          // tell printer driver that dmPapersize field contains
          // data it needs to inspect.
          dmFields := dmFields or DM_PAPERSIZE;
        End;
     finally
       // unlock devmode handle.
       GlobalUnlock( Devmode );
     end;
    End; { If }

source: http://www.efg2.com/Lab/Library/UseNet/2000/0314.txt