There are two ways of using the T-Mobile Multimedia Net Card on Mac. You can either download (and pay for) Mobile High Speed 3G which requries you to reboot during the installation or you use my modem script.
You need to download the modem script to the "Modem Scripts" folder first and assign the proper permissions. To do this paste the following into Terminal.app:
cd /Library/Modem\ Scripts/
sudo curl -o "T-Mobile Cellular" http://www.robertlacroix.com/files/T-Mobile%20Cellular
sudo chmod 664 T-Mobile\ Cellular
1. Disable PIN request on your T-Mobile GSM card, you won't be able to enter it :)
2. Plug in the Multimedia Net Card
3. Go to the Network Preference Pane
4. Choose PC Card Serial in the Show dropdown
5. Use the following settings in the PPP tab:
Account Name: t-mobile
Password: t-mobile
Telephone Number: *99#
6. Choose Modem T-Mobile Cellular
Wait till the LED on the Net Card flashes blue for UMTS or green for GPRS and connect :)