Custom scoring example

[Ravindra Sharma]

I am looking for an example if anyone has done any custom scoring with
Solr/Lucene.

I need to implement a Query similar to DisjunctionMaxQuery, the only
difference would
be it should score based on sum of score of sub queries' scores instead of
max.

Any custom scoring example will help.

(On one hand, DisjunctionMaxQuery itself is an example :-). It is too
professional :-)

Thanks,
Ravi