multistrap in native mode - howto switch configuration step off

Hello Neil and mailinglist,

<off topic>
Thanks for your hard work on releasing Grip 2.0.3 !
</off topic>

Today a tried to built a rootfs on an i386 platform for an lxc container 
(so we have the same architectures on both sides).

The configuration is done automatically right after unpacking. But I 
like to reuse my tested Makefile snippets [1], which already took care 
of bind mounting /proc etc in the targetfs, so the configuration for 
packages which need those won't fail.

Is there a way to swich the configuration step off in native mode (I'm 
using mutlitrap from stable-backports.)?

Thanks and kind regards,
Marcus

[0] http://gitorious.org/dockstar/emdebian-multistrap