apache_solr solr forum

I'm quite busy trying to get the latest (dev) Apache_Solr module to work with our complex multi site setup and it all went fine, until we had to import an huge phpbb2 forum (28k topics, near 1 million comments - some topic has thousands of comments).

Now I'm puzzled: which route should I go through? Does anyone has succesfully implemented something like that?

From the top of my mind, I'd consider each comment as a separate document to feed SOLR with, with a rightly cooked "indexer" script that will extract them AND the topic, of course (first the topics, then the comments).