I have completed developing my custom theme in magento and now I want to make it installable or I want to package my design like other magento themes so that I can just put it in htdocs and go through the installation steps to install that custom theme. Can any body provide me a clue on how to make the custom theme installable?
Im pretty sure this is what you are looking. Themes are packed just like extensions to be installed with Magento Connect. The link i posted is the official guide to pack extensions and themes in Magento.