Possible to pre-release single blog in multi user version?

We have a multi site installation that is not yet ready for general roll-out and the whole site is currently password protected (local .htpasswd file and Directory statement in httpd.conf). What I need to do is release one blog to be globally visible while continuing to keep the remaining blogs and the login page (where any user can authenticate and create new blogs ) protected. I thought I could do this with a local .htaccess/allow from all in the individual blog folder but no matter what I do apache doesn’t seem to see or implement it (and I know that the file path and url are different).

Has anyone else done this and have any advice to offer (including an alternate method of pre-releasing just the one blog out of a nulti-site installation)? Thanks very much