Hello,
I also have 05' X5 with my bluetooth phone and pretty sure bluetooth option is a standard option from 05'
there is no pairing button at the center console armrest, and no need to press button for 3 seconds.
just use your phone. go to bluetooth menu from your phone and run search.
then your phone will find BMWXXXXX, chose it and it will ask you the passkey.
that's how I use my bluetooth phone with my X5.
and also, take a look here.
http://bimmer.roadfly.com/bmw/forums/e46/5736187-3.html
hope it works!