This document gives you all the needed steps to deploy the [LESS css pre-processor] (http://lesscss.org/ "LESS css pre-processor") on your Drupal installation. The following given commands assume that you have Drush installed.
To achieve this, you only need to go into your Drupal installation folder and type:
drush dl less
to download the LESS module
drush en less -y
to enable the LESS module