>> to build a handful of packages on 
>> NetBSD-Y-i386, with the target of NetBSD-X-i386
 >
> It's not really possible for packages....  at least not yet.
> 
> Packages are built with the build-host's toolchain, source headers, and
> libraries, and so they are always specific to the build host's currently
> installed and running OS release.

OK, I see. This may be nice having mentioned in the pkgsrc documentation.

Anyway, is it a possible way to go to set up a NetBSD-X environment 
within a directory of the build machine, and use it with chroot to 
build? I guess in this case the only thing that would still be other (Y) 
version in the environment is the kernel.

If this is possible, how should I start realizing it?

byez
mortee