that no "firmware" will fix. When we read the Canon HF100 manual
http://gdlp01.c-wss.com/gds/7/0300000907/01/hf10-100nim-en.pdf
and turn to page 122 in the Specifications section, we see that the mic terminal wants a mic that drives "-57 dBV (with 600 ohm microphone)/ 5 kohms or more" and requires a 3.5mm (1/8") stereo minijack."