Only show last 5 posts. Password Protect older posts.

Is there any way to only allow public viewing (via search/archive links/homepage etc…) of you “x” number (five?) most recent posts, while requiring a password to protect everything except the subject line of your older posts? I found something that lets you set a password for everything other than your most recent post. I installed it, but it didn’t even work for that. I’d like to be able to choose the number of posts to be viewable without a password.