So far, installation of Adminer is phenomenal compared to PMA. However;
The documentation on using plugins leaves something to be desired. I get the part about creating a php file, and then specifying which plugins to enable. But where are the plugin files located? Do I need to get them somewhere? Where should they go on the server? What should this php file be named, where should it be placed?
Basically what you are doing is creating an alternate file to run which sub-classes and customizes the main program. So the php filename could be something like 'my-adminer.php' and by virtue of the include statement at the bottom of it, it runs the main program with your customizations.
Take a look at http://www.adminer.org/en/plugins/#use. The classes with plugins may be located anywhere you want but you need to include them in adminer_object().