wget http://pecl.php.net/get/xhprof-0.9.2.tgz
tar -xzf xhprof-0.9.2.tgz
cd xhprof-0.9.2/extension
/Applications/MAMP/bin/php5.3/bin/phpize
./configure
make
cp modules/xhprof.so $(/Applications/MAMP/bin/php5.3/bin/php-config --extension-dir)/
echo "extension=xhprof.so" >> /Applications/MAMP/conf/php5.3/php.ini