If you are using a Debian sarge system (currently the stable release) with php4-pear installed, you will still not have a pecl command.
The fix to this is to upgrade pear.
Unfortunately, pear upgrade PEAR will also error out stating that you need pear-1.3.3 minimum.
The fix to this is to specify the version of pear that you want to install. In case it wasn't obvious, that means you want to
pear upgrade PEAR-1.3.3