You may increase a bit the reaction time of the AI, for example to 0.5 secs (last parameter of mando_missileecm.sqf),
you may also play with mando_minchaffdist global which is also third parameter of mando_missileinit.sqf. If missile distance to target + mando_minchaffdist is less than missile distance to chaff/flares, the missile will follow the target.
By default it is = 0, if you decrease it, it will be quite hard to avoid missiles (you will need to drop flares and break hard horizontally or vertically while keeping fast), if you decrease this value (< 0), avoiding missiles will be easier.
You may also set this value per missile type (very last parameter which is optional, see mando_missile.sqf header for more info). So you may create your own launcher copying and modifying mando_hawk.sqs so that the missiles have more or less tendendy to follow contermeasures instead of the real target.