Agree with x14, have a look at this
http://www.blackberryforums.com/bes-...-contacts.html
Assuming your BES is 4.1.6 and HH 4.5 above (not sure about other versions) BBM contacts ought to be repopulated when an EA switches a handheld for a user.
It's not quite the same as being able to push a list of PINs from BES to BBs, but it should help.