Upon first reading, I took this to be a Network PXE boot, where the image is located on some server on the same subnet located via port 67.
In either case, adding drivers after the boot is possible *IF*
the device containing the BOOT image can be supported without a driver update
and the BIOS supports booting from that device (ie: some do not support booting from a USB connection)
For example, an Ethernet driver can be update and then used *IF* that interface is first disabled, updated and then subsequently enabled.
However, devices for which there are timing issues with an update include
Keyboard, Video, and Mouse as these are tested by the BIOS and immediately
are referenced, thus not able to see or use any updated drivers.
