It is possible to hide the applications mainform from the taskbar or put other forms in your application on the task bar by simply changing the create params as the form is constructed.
Override the Form’s CreateParams and add one of the following to either remove or add to the taskbar
to Show in the taskbar
procedure TForm.CreateParams(var Params: TCreateParams);
begin
ExStyle := ExStyle or WS_EX_APPWINDOW;
end;
to remove from the taskbar
procedure TForm.CreateParams(var Params: TCreateParams);
begin
ExStyle := ExStyle and not WS_EX_APPWINDOW;
end;