autochanger,stalk controls,ipod

my 2004 landmark has an aftermarket Alpine head unit . Consequently the autochanger and steering wheel controls do not work . I can buy a used original head unit and the autochanger & wheel controls should work agin but i dont think it will be ipod / MP3 compatible . Or I can buy an up to date head unit and try fitting a Celsus ASC 2620 adaptor loom to it which should enable the steering wheel controls though i am not sure if it will enable th autochanger as well Anybody been down this road ???? .