Have you looked into just using mkisofs to build the image instead of
mkisofs+mksunbootcd?

mkisofs v1.13 has this capability (-B) , and its already part of the
cdrecord 1.9 package.

On Fri, 1 Dec 2000, Todd Vierling wrote:

> Date: Fri, 1 Dec 2000 10:15:06 -0500 (EST)
> From: Todd Vierling <tv@wasabisystems.com>
> To: Tracy Di Marco White <gendalia@iastate.edu>
> Cc: port-sparc@netbsd.org
> Subject: Re: sparc bootable cd 
> 
> On Fri, 1 Dec 2000, Tracy Di Marco White wrote:
> 
> : I'm trying to build a bootable (multiplatform) cd.  The instructions
> : on the web site say to do:
> 
> The instructions on the web site are a bit out of date.
> 
> I'm in the middle of working on a brand spankin' new CD creation system
> which supports full multiplatform CD generation, and copes with a last
> minute bug in the 1.5 sparc installer.  I will update that webpage as soon
> as the current buglist in that Makefile system is squashed.
> 
> -- 
> -- Todd Vierling <tv@wasabisystems.com>  *  http://www.wasabisystems.com/
> -- Speed, stability, security, and support.  Wasabi NetBSD:  Run with it.
> 
> 

Ron