Mode 1 requires that you create your own dialog resource. You can do this with a variety of utilities, usch as ResEdit or Dialog Creator. You can also write RMaker source code and compile it. The first 4 items must be as specified previously. You must put these resources into the resource fork of the stack, so that DoList can find them. If there is any problem with a resource or if DoList can't find a resource, the results are unpredictable, and can even produce a system bomb. DoList assumes that the resource is present and valid, and does no error checking.
I've included Mode 1 for the people who really want to change the look of the dialog box, and know how to do so. Only the first 4 items are reserved, so extra text items (such as prompts) can be easily added. Those not familiar with dialog resources should not use Mode 1.