Getting Citrix to work on Linux can be tricky - specially since there is no official 64bit client for Linux. However, with a bit of tweaking, it can be made to work. Here's how:
1. Download the Citrix client from the website http://www.citrix.com/English/SS/downloads/details.asp?downloadID=3323&productID=-1 . The current version as of this writing is version 11.100
2. Install the OpenMotif libraries
sudo yum install openmotif openmotif-devel
3. Next we need to install the 32 bit version of libXaw.
sudo yum install libXaw.i686
4. Now install the client. Change directory to the location where the client was downloaded and run:
tar xvf linuxx86-11.100.158406.tar.gz
5. Follow the onscreen instructions to install the client. I installed client at /usr/lib/ICAClient and disabled Gnome and KDE integration as well as USB support.
6. Restart the browser if it was already open and navigate to your Citrix site. When the browser prompts to download the .ica file, select open with /usr/lib/ICAClient/wfica and you should be able to see your remote desktop on screen.
7. Alternatively, download the .ica file and run /usr/lib/ICAClient/wfica /path/to/my.ica (Replace /path/to/my.ica with the real path to your ica file.