wget http://downloads.sourceforge.net/project/libssh2/libssh2-1.2.1.tar.gz?use_mirror=softlayer
 tar -zxvf libssh2-0.12.tar.gz
 cd libssh2-0.12
./configure && make all install

Run the pear installer for PECL/ssh2:

pear install ssh2

If this installing via pear fails,

wget http://pecl.php.net/get/ssh2-0.11.0.tgz
 tar -zxvf ssh2-0.11.tgz
 cd ssh2-0.11
 phpize && ./configure --with-ssh2 && make

Copy ssh2.so to /usr/local/lib/php/extensions/no-debug-non-zts-20020429.

 cp modules/ssh2.so /usr/local/lib/php/extensions/no-debug-non-zts-20020429

Add extension=ssh2.so to /usr/lib/php.ini
Run service restart httpd to enable these changes.