Install stuck at check file permissions

[Guest crake]

I can't install Cubecart because the check for file permissions fails. The installer wants 4 directories to be 777, but my server doesn't allow 777, nor is that necessary. The server is running SuExec. From the server admin:

"Please note that setting the permissions to 777 does not work on our servers, as we are running SuExec that treats such permissions as insecure. Furthermore, SuExec allows your scripts to run under the permissions of your own user, so there is no need to give world-writable permissions to your scripts and folders. If the script you are using has instructions to set the permissions on some files or folders to 777, we suggest that you ignore them and use 775 permissions for all your files."

But this doesn't work, since the installer demands 777 AND there is no way to skip the check. Ugh.

When the admin looked at the install script they reported that they were unable to get around the issue and:

"Unfortunately these permissions cannot be changed. Actually 777 permissions are considered insecure, as they allow every user on the server to modify files with such permissions. You should contact the developers of this software for assistance how to get past this step."

So - I don't need world-write access on those directories for this to work on my server because of how the server treats scripts, but the script doesn't allow this.

Please help!