Password protect one blog in network

Hi All

I am trying to find an effective way to password protect one blog on my wordpress network.

I currently have two sites on the network, the main site and one in a sub folder. The subfolder is the one that needs passowrd protecting.

I simply want to display a login page when trying to access that site.

I found the network privacy plugin which was good but it displays the wordpress admin bar across the top of the page and I would like to avoid this.

I have read online there are ways to password protect a site via htaccess but not sure this is possible on a network.

Any advice would be great.

Thanks