Nikolai,
i'm not quite sure that i fully understand your question and i have no experience with COBOL in a Windows 98 environment, but i reckon that if you have the source code, you should recompile it using a compiler fit for your target environment. That should give you an executable program you can run.
Be aware of conversion problems, though, because sadly one COBOL isn't exactly like the other. But of course, you can again post possible problems on this forum !
Good luck !