Thomas Mortagne said:

An alternative not listed by Guillaume depending on what is your need is to put your groovy code in a wiki macro which is then used from any wiki code (in that case only the wiki macro document require programming right). There is several kinds of "macros" in XWiki, wiki macros as in http://platform.xwiki.org/xwiki/bin/view/DevGuide/WikiMacroTutorial as not deprecated, on the contrary (they actually are components).

This is a very promising route, thanks. Any yes, I did get confused about what was deprecated. I said macros, when I think it's actually plugins that are deprecated.