Any way to update LFS system from cd

I'd like to update my NetBSD 3 and 4 systems that use LFS from the 
NetBSD-4.0-rc3 cd.

The Dell laptop doesn't have a fdd and neither network nor existing 
LFS filesystems are available from the cd boot.

I've done build release on another system but a cd from this will 
have same problem. I can modify INSTALL_LAPTOP to provide kernel with 
required LFS and network support for creation of a custom boot cd, 
but I'm not sure if this will still work with sysinst. Is this likely 
to be ok and will sysinst then be able to use LFS partitions?

Whilst I've previously had some success with a manual install of sets 
using a script, this has also too often left me with having to 
recover an unusable system whilst sysinst from a cd boot has so far 
always gone smoothly which is why it's my preferred method.


David