I am having the same problem. I have tried everything. Both of the suggested scripts including the Mobilebroadbandrocks + the launch2net software and which as whmcp says, results in a modem initalisation error.
I even purchased an EU850D card with integral SIM, but this is not even seen by Mac OS
I am in the UK, and the problem is with the Vodafone model.
Mac OS X10.5.6 runs great - its really fast installed on a Runcore 32GB
SSD
If I could crack this problem, it would be the perfect Mini Macbook & truly mobile
Any suggestions?