I'd like to set up a cold storage wallet that has the ability to create and sign transactions offline. It seems both Icebox and ethkey has this functionality, but I'd prefer to have the option to easily move the keys into Mist at a future date, without importing the raw private key.

So, naturally that brings me to Geth. This post shows it's possible to sign arbitrary data with an RPC call, but what about an entire transaction? Is there a specific method for this, or is it just a matter of throwing in the correct raw data?

Any help would be appreciated. Thanks!