You don't need port forward for the cameras - you simply need a port forward (OR VPN if you're paranoid) to the Diskstation itself.
Adappted: Thanks. Would something like this be a good option? http://www.newegg.com/Product/Product.aspx?Item=N82E16833704130
Would I then basically then have my orcon genius plug directly to this, then my home network to it? I then configure this VPN device to allow connections only from my macbook pro's macaddress. I then securely enter into my entire home network?