The XOR part seems pretty straight forward, but generating a truly random amount of text would seem to be the hard part in making the key.
http://cryptomuseum.com/crypto/vernam.htm
Magnum,
The German Enigma was essentially a vernam machine, but instead of the tape, it used a set of disks which could be re-arranged and set to different starting positions,and these elements implemented a pseudo random number generator to replace the tape.
The random one time pad was the real problem, creation, distribution, destruction, etc.
Dave.