Backup your site files and your db

Rename all the YOUR TEMPLATE folders to match your custom template name.
(In both the includes folder and the overrides-writes folder).

Upload the includes folder.

Upload the folders inside the overrides-writes folder.
(First check to make sure are not already overriding any of these files. If so, merge them together).

Install the SQL patch.

In Admin, make sure you are using the split-login format.

That's it.