The Zumo 550 (infact the entire range) has a 3.5mm jack socket either on the motorcycle mount or on a flying lead (660) that you can plug all sorts of headphones or in-ear monitors straight into it.
However your Autocom should make it easier because you can get a lead (part 1314 I think) that connects the Autocom unit to the Zumo cradle.
Needless to say things may be different dependant on the Autocom version that you have but an Outfit like Chainspeed will be able to advise you.