How do i install drush for a drupal site which is on shared hosting? I have a shared hosting account on which i have created sites using joomla 2.5 and drupal 7.

I want to use drush to apply patches to existing modules for my drupal 7 site. 

Can any one guide me as to how can i install this drush and use it for these drupal 7 sites on my shared hosting ?

Step by Step Guide would be highly appreciated (New here) 

Thanks
When I google "install drush on shared hosting", the two top hits are exactly what you are looking for.


Learning How to Install Drush on a Non-Admin Rights Server
Installing Drush on Shared Hosting Accounts