I'd hoped to have written the bulk of human knowledge to Freebase by now, but I came to a screeching halt when I found that I'd need cookies and sessions and such.
That is, you have to authenticate to write data in bulk to Freebase. Here's one way to do so using OAuth and PHP.
1. Sign in to Freebase and register an app. Take note of your Consumer Key and Consumer Secret.
2. Get oauth-php and add it to a directory where your code can see it.