lucene ranking question

[Akanksha Baid]

My query is a document and my index also contains the document in a 
field. There maybe some formatting differences between the two 
representations , but largely both versions of the document should be 
fairly similar. Using the current scoring function is not giving me good 
results since I am not doing a keyword to document match.  What would be 
a good way  to match a document to a document using Lucene.

Appreciate the help.
Thanks!
Akanksha