I have not used Pressflow. But have vanilla installed Drupal 20+ times and have recently begun with Distros like Atrium, Acquia, UberDrupal, OpenPublish.
I am working on my first Acquia Drupal distro (
http://acquia.com/products-services/acquia-drupal) on MAMP and have Solr working with faceted search. Using Acquia I was able to do this very easily.
The distro includes everything you need except Solr 1.4. (USE 1.4!) which you can get here:
http://www.apache.org/dyn/closer.cgi/lucene/solr/
Place it somewhere not visible to the web (not in your apache docroot and not inside of your drupal directory).
Then you only have to move 2 files from the drupal Solr module:
schema.xml
solrconfig.xml
into
apache-solr-nightly/example/solr/conf/schema.xml
apache-solr-nightly/example/solr/conf/solrconfig.xml
(move the existing ones somewhere else first - as per README)
then run java -jar start.jar in shell and you should be up and running.