I use a centos 6.0. How can I print to the Xerox printer from my applications -- like LibreOffice, emacs, eclipse, chrome, etc ?
You cannot add printer to an applicataion because a printer is an element of the operating system and not of the application. All applictions takes the printers of the operating system.
You may want to add a new printer to your CentOS. Simply go to System -> Administration -> Printer (or Printing), use the Add new printer icon. Follow the instruction. (If your printer is a good network printer, it may be autodetected. Else, note its IP address on a paper and use
Alternatively, you can browse the address 127.0.0.1:631 to have the web interface of CUPS. This interface may be a little harder to use.