Lucene search result clustering

[Max]

Hi list,
I would like to do some Lucene Documents clustering.
I have a 
Lucene index and I run my search on the index.
The search result is 
composed of a list of documents.
How can I translate my list of 
document in a format suitable with Mahout format?
I have seen this 
library contains some clustering algorithms, but they don't provide 
(at 
least I haven't found) any translation from a document to a point.
Do I have to implement this by myself, or does it already exist?
Thanks 
in advance.