手工安装新版本的PHP，只需以下步骤：

1. 下载要安装的PHP版本。既然是用WampServer，那当然是下载Window版本的ZIP包啦：http://windows.php.net。解压到 Wamp的安装目录\bin\php\php5.2.17。这里以5.2.17为例。
2. 进入 Wamp的安装目录\bin\php\php5.2.17 目录，从 php.ini-dist 或者 php.ini-recommended 复制一份，重命名为php.ini，适应修改php.ini配置（如extension_dir），再从php.ini复制一分，重命名为 phpForApache.ini。
3. 从已有的版本目录中复制一份 wampserver.conf。比如我安装WampServer的时候已经有php5.3.0，在 Wamp的安装目录\bin\php\php5.3.0 目录下复制 wampserver.conf 到 Wamp的安装目录\bin\php\php5.2.17。
4. 修改Wamp配置文件：进入 Wamp的安装目录，用IDE或记事本（最好使用行号定位的记事本，如EditPlus等）打开 wampmanager.ini，定位到 335 行，通常在这一行就是[phpVersion]，如果不是，则在附近找找。复制下面一行：
   Type: item; Caption: "5.3.0"; Action: multi; Actions:switchPhp5.3.0
   插入到这一行前面，并修改为

   Type: item; Caption: "5.2.17"; Action: multi; Actions:switchPhp5.2.17

   再复制
   [switchPhp5.3.0]
   Action: service; Service: wampapache; ServiceAction: stop; Flags: ignoreerrors waituntilterminated
   Action: run; FileName: "Wamp的安装目录/bin/php/php5.3.0/php-win.exe";Parameters: "switchPhpVersion.php 5.3.0";WorkingDir: "Wamp的安装目录/scripts"; Flags: waituntilterminated
   Action: run; FileName: "Wamp的安装目录/bin/php/php5.3.0/php-win.exe";Parameters: "-c . refresh.php";WorkingDir: "Wamp的安装目录/scripts"; Flags: waituntilterminated
   Action: run; FileName: "net"; Parameters: "start wampapache"; ShowCmd: hidden; Flags: waituntilterminated
   Action: resetservices
   Action: readconfig;
   插入这一段之前，并修改为
   
   [switchPhp5.2.17]
   Action: service; Service: wampapache; ServiceAction: stop; Flags: ignoreerrors waituntilterminated
   

   Action: run; FileName: "Wamp的安装目录/bin/php/php5.3.0/php-win.exe";Parameters: "switchPhpVersion.php 5.2.17";WorkingDir: "Wamp的安装目录/scripts"; Flags: waituntilterminated
   Action: run; FileName: "Wamp的安装目录/bin/php/php5.3.0/php-win.exe";Parameters: "-c . refresh.php";WorkingDir: "Wamp的安装目录/scripts"; Flags: waituntilterminated

   Action: run; FileName: "net"; Parameters: "start wampapache"; ShowCmd: hidden; Flags: waituntilterminated
   Action: resetservices
   Action: readconfig;
5. 退出WampServer，再重启。完成。