It all depends upon what you mean by "control".
BMLINK allows you to use [N.Music] and [N.Radio] commands from your Beo4 to "talk" to iTunes to:
a) play music from your iTunes collection, skip tracks, and switch between blue, yellow, red etc modes
b) play music from internet radio stations you have defined in iTunes under a playlist of "N.RADIO"
So was BMLink the software you downloaded ?
And what type of Mac are you using (Macbook, MacMini, etc) ?
And have you plugged the BeoPort into (1) the audio headphone jack and (2) the USB port ?
If you want more "control" than what I just described then you probably should take a look at Philippe's LinkPlayer ....
First B&O (1976) was a Beogram 1500 ... latest (2011) change has been to couple the BL11 with the BL6Ks *sounds superb*