TI Launchpad USB serial comms in OSX
The drivers for the TUSB3410 for Mac OS X are still in beta. You should consider contact TI about this and maybe they can try to fix your problem. Even if they aren't currently interested in pushing the Mac side, the more interest they get from Mac users the more likely they are to do something.

I also found a few comments about how there are open source version of the driver, but was unable to find any of them. Maybe you will have better luck looking for them.