This thread should answer your question:
http://mail-index.netbsd.org/current-users/2002/01/02/0005.html

The short is that it's not supported.

You can either build on a faster, binary-compatible port, or do it
directly on your hpcmips machine. You could nfs export pkgsrc from
another machine and do the usual package building. Sure it's slow, but
it works.

-Steve

On Thu, 2 Oct 2003 15:11:56 -0500
"Andrew L. Gould" <algould@datawok.com> wrote:

> I've been reading the online documentation regarding cross compiling
> and Michael Lucas' "Palmtop NetBSD" article at:
> http://www.onlamp.com/pub/a/bsd/2003/06/05/Big_Scary_Daemons.html
> 
> I haven't found any documentation that specifically addresses cross
> compiling packages.  (I'm not a programmer; so it's possible that I've
> been staring at it without knowing it.)  Is the technique the same as
> compiling the kernel?  In other words,  would the following work:
> 
> 1. cd /usr/src
> 2. ./build.sh  -m hpcmips  -D /usr/hpcmips-distro  -T
> /usr/hpcmips-tools 3. cd to the application's pkgsrc directory
> 4. /usr/hpcmips-tools/nbmake-hpcmips package
> 
> The pkgsrc directory is for i386 pkgsrc.  Is this a problem?
> 
> On a separate note, I tried step 2 without the -D option to build the
> tools, but I got an error message about needing a directory other than
> root.  Did I miss something?
> 
> Thanks,
> 
> Andrew Gould