Well, here's the easy way. Inside the zip folder is a php script which does not require mysql access nor ftp (all that fancy stuff) It has an input box for the password and checks that in the script. If the password is correct it will show the protected contents, if not it asks for the password again. You would have to physically set up each folder or link and apply the php to each, but once it is set up, the passwords don't change unless you change them and you only need to change whatever the link or protected content happens to be. If you use a link you would simply have to change the content in that spot. That would probably be the easiest way. If you want user names and all that jazz, a mysql database will have to be set up with php scripting. This way is free.
Just give each client their own link to their own copy of this php file with their password in it and get rid of the box on your home page altogether. That can be set up in the same manner, so to speak, if you choose to do so.
I'm making it sound confusing, sorry, open up the readme text in the zip and it's fairly simple.
Anyone else may feel free to use this for anything as well.