I wanted something like this as well  -- as a work-around I made an alias "pluginaliases" that gives various options:
1000>>>pluginaliases>->Open Plugins Folder | explorer.exe %FARRDIR%\Plugins>n>List Plugins | restartsearch aplugins>n>Reload Plugins | restartsearch goreload
I have a hotkey that brings up FARR and sets the text to "pluginaliases".
Admittedly, this may not help in locating the specific folder under which FARR is looking for Plugins...
 I'd also like an alias for bringing up the Plugin Manager dialog -- may be there is one and I just haven't found it