You may not be able to avoid proper re-installs. In particular some panel-based tools create custom sub-folders and scatter sub-scripts across different default AE folders due to how AE loads these panels in general. Of course on the face of it just copy & paste-ing should still work, it will likely just require to dig for more than one single folder.
I have a bunch of custom presets stored in a dropbox folder. I created an alias to that folder and put the alias in the directory (folder) used when you create and save an animation preset to the default location. On a Mac, that folder is the User/Documents/Adobe/After Effects 2000/User Presents folder
AE keeps track of that folder through updates and when installing new versions. I do the same thing with the folders used for Scripts and any other folders that are used to store things that I might need. My preference files are also synced. No matter where I am my machines are always all synced up. The only thing that is not automatic are the updates and new installations of 3rd party effects and scripts that require installers.