Thank you, now it boots.
Here's what's inside my /etc/grub.d/40_custom now:
------------------------------
#!/bin/sh -e
cat << EOF
menuentry "NetBSD 7.0" {
insmod ufs2
set root=(hd0,msdos2)
knetbsd /netbsd --root=wd0a
}
EOF
------------------------------
Mitt