The configuration of Tunnelblick is really easy. From the IPFire web interface go to Services > OpenVPN. Look for the Connection Status and Control section:
Download your client package by clicking on to "Download Client Package (zip)". The client package should now be in the Mac Download folder.
TIP: Add the extension of ".tblk" at the end of the folder name. When you do this the icon for the folder will change from a folder icon to an icon for a Tunnelblick VPN Configuration. To install, double click the folder's new icon. Or Drag and Drop the folder's new icon onto the Tunnelblick icon in the menu bar to install it.
Launch Tunnelblick.app and click on the Tunnelblick icon in the upper menu, then connect to the new profile.
FIXME - Now you get asked about the password you have chosen on your IPfire bevore. After the correct input oft this password and a correct creation of the certificate the client will connect to the IPfire.