I do know that dosemu can emulate a 386 and a 486 well enough to fool a few programs I have. I also know that you can configure what the COM ports point to in terms of Linux files in the /dev directory (make COM2 point to /dev/modem, for example), so if you can see the device from inside Linux, you’ll be able to see it inside dosemu.
Only being able to find binary drivers compiled for DOS or MS-Windows is crap Linux enthusiasts have to put up with. I have faith in dosemu, however.
An interesting thing you can do is get a freeware CP/M emulator for DOS and run it inside dosemu. I’ve done it and gotten acceptable speeds. (Google for the software, it’s easy to find.) This has gotten easier since Corel, which now owns the Digital Research properties, has put all flavors of CP/M into the public domain. Both binary and source distros exist for free download.