Are there any instructions anywhere for adding a w3 plug-in? Not adding w3 to WordPress, but w3 seems to have an entire plug-in system of it's own.
The reason I ask is because currently my company has multiple WordPress installs setup under the same hostname. So when memcached is turned on the cache_key ends up being the same for all of the blogs and on queries such as 'select * from wp_users where user_id = 6' you end up with wrong results on all but one blog. I want to use the w3 action hook called 'w3tc_dbcache_cache_key'.
Let me know if you have any suggestions other than 'use WP multisite' and 'change the location of the blogs'.