DFly installer needs option to ovewrite system binaries while keep user installed programs and data

[Tomaž Borštnar <tomaz.borstnar@xxxxxxxx>]

Been fighting with dreadful "Panic: stack overflow" for too long (more than an hour) :( Anyway, I often used Upgrade feature of 
FreeBSD sysinstall which just replaced the system files and kept user data and settings intact. DFly installled NEEDS this too :) 
With feature like this I would just boot from live cd and replace boot loader code (plus other files) and all would be fine.

So what is the proper sequence to replace boot code after doing installworld?
pre-1) copy original /boot to /boot.orig
1) copy /boot.orig to /boot
2) disklabel -B -b /boot/boot1 -s /boot/boot2 /dev/<proper-disk-device+slice>

But does not seem to work :(

Need to check what does make installworld do to install bad code...

Tomaž