Cross compiling a program

[AGC <agcarver+netbsd%acarver.net@localhost>]

Is there a helpful document somewhere that describes the process of 
cross compiling a program for use under NetBSD/sparc?

I want to compile newer versions of gpsd but the project maintainers 
have switched away from configure scripts to python and SCons, neither 
of which will compile and install for NetBSD/sparc.  I do have, however, 
several Debian/x86 systems that have working versions of both of those 
programs.  I want to be able to compile gpsd on one of those Debian 
systems but generate a NetBSD/sparc binary.

Most of the documentation discusses cross compiling NetBSD itself (which 
I may do later if I can't figure out how to upgrade NetBSD in place, but 
that's a totally different effort that I'm having trouble following).  I 
don't see anything about individual programs that are downloaded from 
source.