The first thing to do is install libftdi, an open source version of the ftdi USB drivers. I installed these onto a 64 bit machine, so I used the following command in Gentoo Linux.

ACCEPT_KEYWORDS="amd64" emerge -av libftdi

This installed version 0.9 of the libftdi drivers.
Next we will get the current version of OpenOCD from the svn repository. You must have subversion installed on your system to complete this command successfully. Make sure to move to the directory you would like the OpenOCD source moved to.

svn checkout http://svn.berlios.de/svnroot/repos/openocd/branches/cortex-m3

In the current directory run the following commands.

./bootstrap
./configure --enable-ft2232-libftdi
make
make install

There are sample configuration files in the doc directory. copy the cortex-m3 one into the src directory with the following command.

cp doc/configs/cortex-ft2232.cfg src/openocd.cfg

Or copy the config file into another directory where you would like to run the openocd executable from.
Next start up OpenOCD. Remember to have the USB cable connected to the EV board before executing. Check dmesg to make sure that the EV board is connected.

cd src
./openocd

From another terminal window telnet into openocd.

telnet localhost 4444

You should see the following message if all is well.

Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Open On-Chip Debugger
>

Type help at the prompt to get a list of commands.
If you want to change the telnet port from 4444 edit the config file we copied.

There is also information on setting up OpenOCD using the closed source drivers from FTDI, as well as more detailed instructions for setting up OpenOCD and the GNU compiler for use with the Cortex-M3 core at the following site:
http://www.moteprime.org/article.php?id=27