Download, unzip, upload via ftp (doing so for the last time in your life) or: if you have oneclick version 0.42, just use the zip file.
If it doesen’t work right away, (might not work on 1% of the hosts, you may need to chmod to 755. To do this, use a ftp client like filezilla, and right click, choose “file attributes”, and set write permissions for group.
Test the install by uploading a plugin from your hard disk. If this works, the plugin is working.