NOTE: Testing has confirmed that this version DOES work with the BitmainTech Antminer U3, although There are occasionally some complications. Please see the forum for more details as this will improve in the near future.
Luke-jr (https://github.com/luke-jr/bfgminer) has updated the bfgminer source with Bitmain Antminer U3 support, although it has not yet reached a released version. I've compiled the latest source in advance of the bfgminer 5.2 release, which includes support for the U3!
Please try using your Antminer in the FPGA/ASIC window of this beta version of MacMiner based on 1.5.25
Use the FPGA/ASIC window, click the cog to open it's options and either check the 'antminer' check box or add
in the manual flags
The bfgminer U3 support has only been thoroughly tested on Linux, but as Mac OS has many similarities it should work here just as well. Just plug in and start up the FPGA/ASIC window - let me know how it goes here: http://fabulouspanda.co.uk/forum/