Here is my Mi-8MTV2 layout for the Warthog HOTAS using Polaris & Schnix custom profiles as a base layout with some additional info on the Mi-8MTV2.
Place the .dff files anywhere you want, ex: your Mi-8 input file, and load the input under the correct controller in the controller setup in the game settings. In addition, You will need to add a "Modifier" for the Joystick lever (button 4) button under controller setup. The modifier add should be on the bottom left side of the controller setup. Just rename "button 4" to "Lever" and add. Now when you hold the lever, it should access the second function you programmed in.
I've also added a PDF with weapon/countermeasures/jettison implementation procedures and info. The information are highlights from Chuck's MI-8MTV2 Guide. I hope you find this setup and information useful.