I guess if you re-think the process of an installation, it's not technically ipossible.
You see, ubuntu is a live cd, this means that the tools needed to do the configuration are available at all times, even before packages are copied. In our case, we have our tools needed in the initrd that we use to boot into the live system and then use these to execute the install process.
But, if you're working with a live cd, there is really no reason to wait until the files are copied to perform the configuration. This is why they ask for user names, passwords, localization settings, etc before any packages are copied into the system. These values must be kept somewhere and must execute during the install process.
In a live system, you should have the tools needed to configure the bootloader. They normally hide these settings by defaulting to /dev/[hs]da, but they have the grub commands available to begin with, so they can easily just run `grub-install /dev/[hs]da` and when the installation copletes, just run `update-grub` to update the OS listings.
It's certainly not impossible, and given multi-threaded and multi-processor processing, not even that complicated.
So, "how come we dont have this in our installer?" you ask
The VL GUI installer is written in Gambas2, which was probably not the best choice, but seemed easy enough at the time.
Definitely something we can do and not only match, but beat it.