Informix and Microsoft C 6.0

I have a rather urgent problem... I'm setting up Informix on a DOS-Unix network. I need to compile a new "fglgo" p-code runner on the DOS system, but I am using Microsoft C 6.0 Of course the manuals say that only C versions 5.0/5.1 are supported, but I don't have access to them. Now I can compile a new real-mode runner, and it works ok on small programs. The problem is when I want to run a large program (say a 300k .4gi file). I really need to compile a protected mode runner to use some of that 3M extended memory I have sitting there. Does anybody have any clues as to how I might be able to coax cfglgo (or some variation) to create a protected mode fglgo? My software versions are: PC: DOS 5.0, RDS/I-net 2.10.06E Unix: I-net/SE 4.00.UE1 Thanks for any suggestions... Hugh.