i am also trying to add some custom fields to the lucene index, by modifying the plugin source.
for some reason the method Indexupdater.addToIndex crashes, when it tries to do

data.addDataToLuceneDocument (luceneDoc, doc, context);
writer.addDocument (luceneDoc); //crashes here

but maybe when I get it to work, i can add a few words about it in the Lucene plugin page ? That s something that people might need when they deploy xwiki (search on certain object fields in a page, thus requiring another field in the Lucene Index).
Maybe I can write a tutorial on this (metadata search in xwiki), since i guess it would provide a good example for people who are new to plugins (and i think the plugin doc is a bit ... sober :-) )
I however dont think i will have time to devote to testing hooks, so i dont want to write anything on that if i cant test it myself.

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Jean-Vivien MAURICE
Elève Ingénieur Informatique et Gestion, Polytech'Montpellier (ISIM)
E-mail : jvivien.m2@wanadoo.fr
Tél. : 0046 7 62 33 20 46
Skype : jean.vivien