[webizen]

you need to build extension from source along with phpize from lsphp5 (i.e. /usr/local/lsws/lsphp5/bin/phpize)

download source
tar zxf memcache-xxx.tgz
cd memcache-xxx
/usr/local/lsws/lsphp5/bin/phpize && ./configure --enable-memcache --with-php-config=/usr/local/lsws/lsphp5/bin/php-config && make && make install
add line "extension=memcache.so" in to php.ini used by lsphp5
restart lsws to pick it up.