Have a look here buddy:
How to install Omnikey readers on Linux PC and scroll down to Unbuntu way.....
Follow the instructions posted by master G, 64 bit processor should make no difference..... when you have completed this FTP the attached file I have posted for you (which is already edited) to etc/opensc
Do a reboot, and then type sudo lsusb you should see the omnikey reader listed.......

