Follow the AR42728 . Note that it is now applicable to 14.4/2012.4. The current version of libusb at this writing is 1.0.9, no big deal.
For the next steps, take all the default options...
- cd to /opt/Xilinx/14.4/ISE_DS/ISE/bin/lin64/digilent
- cd to /digilent.adept.runtime_2.9.9-x86_64, run the install script with root permission
- cd to /ftdi.drivers_1.0.4-x86_64, run the install script with root permission
- cd to /libCseDigilent_2.2.10-x86_64, run the install script without root permission
Update 2013-06-11: Be sure to look at the updated Xilinx Answer record AR54382. With Vivado 2013.2 just about out the door, this is where you want to start to get your hardware session straight!