We've been through this before (it would've been helpful id Karim had posted a link) - I don't think that any of the standard SDCC builds will run on true, 16-bit, vanilla MS-DOS as Karim requires:

http://www.8052.com/forum/read.phtml?id=71196

Of course, as I said before, as it's open-source, he could always do his own build for MS-DOS...