Here is my submission to the bounty:
https://steemit.com/steem/@holger80/multisignature-transaction-guide-for-beempy

I used the account @testholger. The 5 Steem were broadcastet signed by the 3 key in this transaction_id:
https://steemd.com/tx/b87bddc02c611de3c6c93161c530561c98a6a6a3