This weekend I purchased an EVDO PC Card. I'm using it in my MacBook Pro. I would like it to automatically to connect to the internet (it uses PPP) whenever I insert the card or wake up my laptop. I'm using "Internet Connect" that is built into OS X 10.4.11.
http://www.evdoforums.com/thread848.html
If the MAC supports NDIS you can use that to supply the "credentials" needed.
Sorry, just don't use MAC enough to be specific. Linux and Windows but simply not familiar enough with OSX.
Good Luck, hope that helps point you in the right direction for a good answer.