Late response, but was looking into doing this for myself, this coming up as one of the results in my searching wanted to provide 2 solutions since I ultimately came to both on my own.
Solution #1
The simple way is to go a round about way by writing a wrapper file to execute the script you're working on. Create a file with the following code:
#!/usr/bin/php
<?php
include('name-of-php-script.php');
?>
Save it as wrapper.command The name wrapper isn't important, but the command extension tells Finder that this is a shell script to open up in Terminal. The file itself just executes whatever php script is in the include.
Solution #2
The specific inquiry requires a bit of work.
First make sure that the 1st line of the php script is:
#!/usr/bin/php
This is where the preinstalled version of PHP is installed on Mac OS X. You can always verify by running this command in terminal:
whereis php
Once you've added the Shebang line to the php script you've readied it for automatic execution.
To make it double clickable executeable you have to do the following:
Right click on the PHP script and click Get Info. Click where it says Open With, click the default option to see all the available options. Select Other...
Switch where it says Enable: from Recommended Applications to All Applications, and click the checkbox for Always Open With. Choose Terminal as the application. Finally, you have to click the button that says Change All...
OS X will verify you want it to set Terminal as the default application to open .php files
This will make every php file open up in terminal by default, but unless they contain the #!/usr/bin/php line they won't actually run.