Can't you just convert dice results to a private key yourself and import that into Armory?
Now I feel really lazy but is there any simple way to do this? Any offline open source tools available to do this? Or how exactly do I convert dice results into a private key?
You probably don't want to create a single private key but a complete armory wallet with deterministic keys.
I've created a simple java app some months ago that creates Armory paper backup codes from any text input. I've used it to create a deterministic armory wallet from a very long and specific sentence. No need for a paper backup this way. When I'm in trouble I can escape to Nicaragua without any usb-stick and recover my XBT by just buying a laptop, downloading the JAR file from github and feed it with my passphrase.
It may be not 100% what you're looking for because it uses a string as input, but it's open source and you could tweak it for your needs. The code base is very small.
Source code:
https://github.com/trapp/brainwalletBinary Download:
https://github.com/trapp/brainwallet/releases/download/1.0.0/BrainWallet.jarThe app works completely offline and doesn't communicate with anything but as always be careful: Read the code and compile it by yourself to be absolutely sure or use it only in an offline environment.