If you are not allowed shell access or do not want to try, there might be a solution for you extract the archive on the server.

I do not recommend the FTP install method when you extract all files to you computer and then upload all files one by one with a program like FileZilla. It is pointless to extract files, is very slow, and can introduce errors.

Try looking around the control/administration area of your hosting provider. Mine is 1&1, and they have something called WebspaceExplorer. Two things about WebspaceExplorer are fabulous: first, it can move files or directories around (FTP method is much more stupid), and second, it can extract zip files.

It cannot extract .tar.gz files, however, but that is where another good program, WinRAR, comes in. In WinRAR, select the .tar.gz archive and select Tools>Convert Archives. Under "Compression", select ZIP, and create the zip file. Upload the zip file with FileZilla, and then extract it to "/" with WebspaceExplorer. Much faster!

 

If your hosting provider has Secure Shell (SSH), you can use that as well. http://wiki.cmsmadesimple.org/index.php/User_Handbook/Installation/Shell_Install