Add the field "EQ" to your library using Tools->Options->Library->Add. It should be a Standard String, and I suggest putting it in the Audio category, but that's up to you. If you don't add it yourself, the version 2+ plugins will add it for you (but the SDK function adds it to all media types, not just audio).
Run the plugin from Tools->Plugin Manager->Interface Plugins. Select the plugin and hit the "Start" button. The plugin will now appear in the activity tree on the left, under Plugins. Click on EQdb to see the dialog.
It works for me. May not work for you. No warranty is implied. See the GNU public license.
Add files to Playing Now. Use the Mixer to select presets or custom EQ settings. Use the Save/Save To All/Remove/Remove From All buttons to save or remove the current Mixer settings to the files in the Playing Now list. The EQ settings are stored as an ASCII string, where "0" (zero) is the highest setting and "n" is the lowest setting. This is the same string that the Mixer uses to store presets in the registry.
As long as the plugin is running (you can stop it from Tools->Plugin Manager->Interface->EQdb->Stop), it will update the EQ settings for each track as it plays. Each track can have it's own settings. You can still turn on and off the Mixer separately.
When the current file has no setting, the plugin defaults to flat EQ settings.