If you don't have it, you can download it from Microsoft's site. Create a directory of your choice and place the file there. Run mdkdem95.exe to start the '95 version of the game. Change to the directory that you decompressed MDK into. Now type 'MDKdemo' to start the game.
More information is in the readme.txt file that is included in the demo.
This was the big hands-down winner of all of your requests, and I'm now happy to say that we have it up and working. We have also put in a switch so that the mouse Y axis can be reversed in sniper mode and bombing run mode. Couldn't turbo run using joystick. This has been fixed. Also, you can now select another option than joypad in the DOS version.