Assuming that you already have installed WAMP server in your localhost.
Now follow the following simple steps.
1) Click on the WAMP icon from your task bar. Go to, Apache->Version. if you see your apache version is 2.2.19 or above, that means your server is compatible with PHP 5.4. if you see you have a lower version then go to Apache->Version-Get More. from there install a newer version of Apache.
2) Download the zipped PHP5.4 VC9 x86 Thread Safe from http://windows.php.net/qa/
3) Extract the zip to your wamp\bin\php\php5.4.0alpha1-VC9
4) From your older PHP versions directory ( ex. wamp\bin\php\php5.*.*) copy the files named
and paste them to your new PHP5.4 installation directory
( wamp\bin\php\php5.4.0alpha1-VC9 )
5) Exit the the WAMP server and restart them.
You should see new PHP version (php5.4.0alpha1-VC9) on you wamp list ( PHP->Version )
6) From browser go to http://localhost/?phpinfo=1
At the top, see your PHP version :)