I found this on a forum which worked for me :
http://www.evdoforums.com/thread12573.html
ricket kinda works, but not by using their connection software (but using their drivers). This is what I had to do from a fresh install of SL (I may be missing some steps).
Install the software. Mac OS will complain that the installer installed stuff incorrectly.
Move the CDFree* and DevGuruVsp* kexts from /System/Library/Extensions to the desktop.
Delete the panther versions
Rename the tiger versions to CDFree.kext and DevGuruVsp.kext
Copy them to /Library/Extensions
Go into terminal, and fix permissions in the the /Library/Extensions directory:
cd /Library/Extensions
sudo chown -R root:wheel *
sudo chmod -R 0644 *
Load the driver:
sudo kextload -v *
Then at some point, either by removing and inserting the USB adapter, or playing around with the Software, I got a popup saying that a new network adapter was detected.
Then, I went into System Preferences, and to the first A600 device, added #777 as the phone number, cricket as the username, and my last 7 digits of my phone number as the password. I was then able to use this device to connect.