So, I tried figuring this out a while ago, never did. Now I’m intent on trying again.
Windows isn’t allowing the Yafaray installer to put files into my scripts folder. When I try and change the folders to read and write capable, Windows just changes them back without notifying me. So, basically, I think that all need are the files that would go in the blender folders, so I can put them there manually. I’ve tried looking for them, but I can’t find them by themselves anywhere.
EDIT:
FINALLY figured that out. Now I have a new problem.
When I click render from the Yafaray export panel, Yafaray opens for a moment, then Blender crashes. This is getting really annoying,
I had a hard time getting Yafaray to work on my Windows XP64, but finally got it to work. I had to install python 2.62 and upgrade to the final version of Blender 2.49.2. That made everything work. You may want to run the installer logged in as admin if you have that option available.