Your friend needs to contact the dealer urgently. If no joy there, apply for a "replacement" registration document to Shannon. When that arrives, he needs to pay the back tax on the vehicle, then sign a delaration in a Garda station that the bike has been off the road for aperiod. When all of this is taken care of, both sign the registration and send it to Shannon to transfer ownership to you.
Don't touch the bike until this is taken care of or you may be getting official communications. Its his responsibility to sort this out. I'm assuming the bike has a valid registration number, an engine number and a VIN plate...