For some reason I cannot get this to work. I have downloaded their .pem file and tried it as a .pem file and as a .crt file using Webmin Configuration/SSL Encryption. I tried uploading it with the Upload Certificate tab and also by uploading it manually and pointing directly to it in the SSL Settings tab. When I try to upload it through the interface it gives me this error - Failed to save new key : Missing or invalid PEM format key.
unable to install an intermediate cert in Webmin from GeoTrust