how to add additional factor at search time to ranking score

[AJ Chen]

My vertical search application will use additional factor for page 
ranking, which is given to each page at search time. I'm trying to 
figure out a good way to integrate this additional dynamic factor into 
the nutch score.  I'll appreciate any suggestions or pointers.

It would be great if I can add some new functions to the nutch code to 
accomplish this. But, if it requires to customize lucene code, that's 
fine. I have tried to use the most recent release (1.4.3) of lucene 
source code, but it did not work.  Is the lucene jar files included in 
the nutch release (0.7.1) very different from lucene 1.4.3?  If yes, is 
it possible to get the source code for lucene used in nutch?

Thanks,
AJ