You would follow the steps in ACP -> System -> Login -> Create New -> LDAP -> fill in the fields. If you have questions, please let us know.
As mentioned previously, you do not need these, nor do we offer anything other than the most recent release. The upgrader does an incremental upgrade of your community. For any customizations, you would need to upgrade these to the latest release in your code yourself following the developers guide. You can post any questions in the Customization forum to be answered by third party developers: https://invisioncommunity.com/forums/forum/500-design-and-customization/ . As customizations are outside our scope of support, we would not be able to answer these in support.