> How do you apply this patch?  I downloaded the source, put xf86-diff in
> the xc directory, and typed patch -p0 xf86-diff , but it didn't do
> anything.  What am I doing wrong?  Thanks.

Download from where?

Try checking out the xsrc module from NetBSD's cvs repository, cd-ing to 
xsrc/xfree/xc and then use that patch command.  Check xsrc/Makefile 
where it talks about USE_XF86_4.

Anyway, I'd like to know what the chances of this building against a 
1.5.2 userland are.

Andrew