I think you would need to get intouch with them, but they normally except 100% of the fee. This enables them to organise your stay, events, security better and pay themselves and helpers as well.
You would need to get intouch with Bougainville Tourism or Papua New Guinea Tourism to assist with reputable operators who are registered on their database.
send me an email on jsmare@gmail.com and I will put you in touch with their officers.
regards
jaive