You should already get this out of the box ... just tack on a wt=json to the
params ie ...
http://localhost:8983/solr/select/?q=*%3A*&version=2.2&start=0&rows=10&indent=on&qt=tvrh&tv=true&tv.tf=true&tv.df=true&tv.positions&tv.offsets=true&wt=json
If you look @ /apache-solr-1.4.0/contrib/velocity
Could you elaborate on your use case? Why do you need a different
format?
XSLT certainly could produce JSON, but that seems a mighty ugly route
to go. The VelocityResponseWriter could also write out JSON, but
maybe what you really want is some basic output that VrW could generate?
Or y
