How to turn off php safe_mode off for a particular directory in a shared hosting environment?

Your service provider might have forgot to tell you that you need to enable your user defined php.ini configuration by adding this line in the .htaccess file that you find in your public_html folder:

#Activates php.ini config located in main folder to work also recursively for all subfolders
suPHP_ConfigPath /home/YOUR_CPANEL_USER_NAME/public_html

Obviously replace YOUR_CPANEL_USER_NAME with your cPanel user name.
I’m supposing your server has got suPHP module(which is quite common in nowdays).

BTW: the php.ini file need to be in /home/YOUR_CPANEL_USER_NAME/public_html too and inside you should write this:

safe_mode = Off

And remember that Safe Mode is deprecated in PHP 5.3.0 and is removed in PHP 6.0.0.