Hamilton, are you aware that you can define the list of plugins per xowiki instance? See:
http://media.wu-wien.ac.at/download/xowiki-doc/index.html#jsnote as well, that starting with xowiki 0.30 xowiki has a multi level configuration: highest precedence have the values in the folder object (these are programmable, can be in principle inherited, computed, etc.) followed by parameters from the package. For more complex configurations, the one-liner field in package parameters is not well suited. If you use a more elaborated configuration, you are most likely configuring the toolbar as well, or you are configuring the stylist (see. the multiple choice example in the documentation above). So, i am not sure, whether the package parameters in the current fashion are suitable for this...
