I wanted to install the zend debugger with eclipse and apache, and found this spanish tutorial, and want to resume the steps I followed:

I assume you have already installed eclipse 3.3 + pdt.

1. Download the corresponding debugger from: http://downloads.zend.com/pdt/server-debugger/, I use amd64 so I got ZendDebugger-5.2.12-linux-glibc23-x86_64.tar.gz.

2. Untar the file in a directory in your home, I used /home/user/Bin/ZendDebugger.

3. Edit your php.ini file and add the following directives:
zend_extension=/home/<user>/Bin/ZendDebigger/5_2_x_comp/ZendDebugger.so
zend_debugger.allow_hosts=127.0.0.1
zend_debugger.expose_remotely=always

4. Verify that the extension is loaded with the simple function:
<?php phpinfo(); ?>

5. Restart eclipse and start debugging!