To use a plugin is easy.
1:start mmoloader/mq2 compile of your choice.
2:start EQ without using the patcher.
3:select a toon and log into game.
4:once in game you can type /plugin mq2(plugin name without the ()). So an example would be /plugin mq2melee
5:some plugins have a UI (user interface) piece, if you get a message saying that the ui piece is loaded but you need to reload your ui, you can just type /reload to reload your ui.
6:read the wiki for slash commands for the plugin you just loaded, some are easy like /melee help.