Easy to do mate.
Contact the fuel supplier in Moresby to pre arrange fuel.. The supply situation changes. You can get it delivered to Daru or Kerima (at a price). Long range tanks are advised.
Fuel out of Horn Island was duty free.. Probably still is. Fill extra jerries and bladder if possible.
Email Australian Border Force Horn Island. They will give you all the forms and requirements. They will give you the contact for the PNG side as well.
Enter PNG via Daru or POM. (You might be able to get it delived to Hagen or Wewak but I’m not sure about that)
Daru and Morsbey and anywhere with road connections can be dangerous re crime, but that’s a separate subject.
A lot of the remote strips from the old days are still on charts but they are now closed.
ATC may let you use a Sat Phone if you don’t have a HF.
It’s easy. I’ve done it a few times.
Fuel is the biggest issue, order it well in advance. And watch out using mogas or any fuel from opened drums, it will almost certainly be cut with something and contaminated.
Flying there is not difficult as long as you are conservative with the weather. If you decided to fly in the hills remember to lean the engine for takeoff.