PL/SLQ: 
function CL_Write( arg_key in varchar2,
                   arg_name in varchar2,
                   arg_value in clob )
                   return integer;

Delphi:
function ClWrite(const ArgKey: string; 
                 const ArgName: string; 
                 ArgValue: TLOBLocator): 
               Double;

var
  LL: TLobLocator;
begin
  LL := TLobLocator.Create(Session, otClob);
  try
    ClWrite (aKey, aName, LL);
    LL.AsString := 'A';
  finally
    LL.Free;
  end;
end;

  function CL_Write( arg_key in varchar2,
                  arg_name in varchar2,
                  arg_value in out clob )
                  return integer
  ...
  ... Retrieve lnPrefKey ...

  insert into g$prefvalues
  ( prefkey_id, name, datatype, clobvalue )
    values
  ( lnPrefKey, bv_arg_name, 'CL', arg_value );

  else

  update g$prefvalues
  set clobvalue = arg_value
  where bv_arg_name = name
        and
        prefkey_id = lnPrefKey;

  ...

update g$prefvalues
  set clobvalue = empty_clob()
  where bv_arg_name = name
  and prefkey_id = lnPrefKey
  returning clobvalue into arg_value;