Synchronizing WP users with .htaccess password protection

I have one blog at domain root and another in a directory below.

WP1: http://example.com/
WP2: http://example.com/anotherblog/

The blog in the folder is for private discussion and document sharing for those who write to the main blog (a kind of intranet). Hence, it is protected with an .htaccess password protection.

Would there be any means to synchronize the WordPress user database with the .htaccess file so that same usernames and passwords would be valid for both? Also, it would be helpful if users could log in to both at once.

There is a plugin that seemingly does exactly this thing (called “no2-htaccess-user-sync”) but apparently it does not work. If someone has ideas how to fix the plugin there is a separate thread to that:

http://wordpress.org/support/topic/plugin-no2-htaccess-user-sync-htpasswd-binary-and-htuser-file

This thread is here for the case that there are some other ways to do the same thing.