Progress use various code pages -- but your output device can only use one code page at a time. If you are required to use a code page that does not support the desired output glyph then, no, there is no way to output the box that you want.
It is sort of like trying to print colored output on a printer that only has black toner. You can send color selection control codes all day long but if your boss refuses to buy colored toner you will only see black output.