WiredNerve,
As someone who has run and appreciates D&D 4th edition, I can definitely say that "Way of the Wicked" was written with the idea that it would not be that difficult to convert.
The maps and plot line basically need no conversion and with the old monster creator, it should be a cinch to convert any monsters.
The area that probably needs the most hands on work is the treasure (Pathfinder and D&D 4th's economies are very different).
Anyways, if you do a conversion, I would love to see any work you care to post.
Thanks for your interest and if you have any further questions, I am eager to hear them.
Gary McBride
Fire Mountain Games