I had to install a magento extension using FTP recently. These 2 blog posts helped me immensely regarding that.
http://www.aschroder.com/2010/05/installing-a-magento-extension-manually-via-ftp-or-ssh/
http://www.groovecommerce.com/ecommerce-blog/magento/developer-toolbox-a-guide-for-installing-magento-extensions/
If you refer these two blogs I am sure you would be able to manually install an extension manually even though you are not a hardcore magento guy.
Magento extensions are normally developed to install through magento connect. But sometimes you will have to install the extension manually using either FTP or SSH. It is said that it's not good to install too many extenions using Magento Connect. Your magento Site could crash.
Magento extensions come up with file structure. You have to upload to the correct location of your magento site installation.
Important things to consider when manually installing a magento extension.
1.) Don't install the extension without testing that in a testing site. Don't install the extension in a live site without testing. Results of the badly design extension could be catastrophic.
2.) Disable the cache prior to the installation.
(System->Cache Management), selecting all caches, clicking ‘disable’ from the drop-down menu, and submitting the change.
3.) Disable the compilation mode.
