Flex - PHPEclipse Plugin

Step 1 :
             Begin the installation from the Flex Builder Help menu item.
      
Step 2 :
             This screenshot show the screen as it initially comes up. In this case you will need to change the radio button to indicate that this is a new install.

Step 3 :
           This screen will vary depending on the features you have installed already. You want to click on the New Remote Site button. If you are behind a proxy and the Flex Builder install mechanism does not work, then you can download a zipped version of the update site and then click the New Local Site button instead.

Step 4 :
           This screen is showing the New Remote Site dialog, filled in with the correct information to install PHPEclipse
           Name : PHPEclipse 1.2.x
           URL :   http://update.phpeclipse.net/update/stable/1.2.x
 
Step 5:
          When you first come back to this screen, if the site you added is NOT selected, be sure to select it before clicking Finish.

Step 6:
          This next screen shows all of the features that are available to install.

Step 7:
          Click the button to accept the license agreement.

Step 8:
          Confirm the install location

Step 9:
          Just a screenshot of the in-process installation.

Step 10:
            This screen is saying that the provider cannot be verified . Ignore that and click on Install All .Not even Eclipse.org nor IBM sign their features.


Step 11:
           Flex Builder needs to be restarted after installing PHPEclipse.

Step 12:
          Finally, after restarting Flex Builder, the first thing you will typically want to do is open the PHPEclipse perspective to check whether it is installed correctly.

Can't install Eclipse plug-ins | Stand-alone Flash Builder

Issue

When you try to install Eclipse plug-ins in the stand-alone version of Flash Builder, you receive the following error:
"To install or update plug-ins, you must quit Flash Builder and run with administrator privileges."

Solution

To install Eclipse plug-ins in the stand-alone version of Flash Builder with administrator privileges, follow these steps:

• In Mac OS X and Windows XP, log in to a user account that has Administrator privileges, and then install the Eclipse plug-ins.
• In Windows Vista and Windows 7, go to the Flash Builder installation location, right-click the Adobe Flash Builder executable and select Run as Administrator. If prompted, authenticate, and then install the Eclipse plug-ins.
  

Reference

http://helpx.adobe.com/flash-builder/kb/cant-install-eclipse-plug-ins.html
http://subeesh.wordpress.com/2008/11/05/installing-phpeclipse-plugin-in-flex-builder/