Now as I understand it the 'old' AFI who had done the appropriate training for applied IF and had passed the flight test could teach the IMC once he/she had the 'No Applied Instrument Instruction' removed from the grey pages of the licence.
Last year when I got my ticket it used to be that an FI(R) could not teach IMC, so I got an AFI also
Now these are fluid times so the rules may of changed, but at the end of the day you will need some instruction on teaching applied IF and pass the skills test.
Enjoy!