I don't use AutoCad, but I would think that you could use any font that you have on your computer with the "Text" tool. Once you have your text there, you will have to explode the text and remove any fill before saving as a .dxf.
A better option may be finding an older version of CorelDraw somewhere like on Ebay.
I'm not sure about a free solution, but you could try "Gimp". http://gimp-win.sourceforge.net/
I'm not sure if it does text in the needed way as I have not had time to check it out. Others may know of some free solutions for you.