Hola,
So I'm working in AutoCAD 2007 and this is what I did. It's fairly simple
#1 Created a Folder in my CAD Standards Folder called Hatch
#2 I renamed the pat file to be called hardwood since that is the name that is inside the pat file and they need to match.
#3 In Options, I added the folder that I previously created in the the Support File Search Path
#4 Finally I went to the hatch command, where it calls the pattern I pressed the icon with the 3 dots and went to custom and there it was. I selected the hardwood pattern and that was it.
I hope this was helpful.
Elsa