To use PEAR and MAMP together run the following command:
/Applications/MAMP/bin/php5/bin/pear config-show
Look up the value of “PEAR directory” in the output and add this directory to include_path in /Applications/MAMP/conf/php5/php.ini
Change the php5 in the paths to php4 if you are using that version for some godforsaken reason.