A module for that would have to be added to Kickstart - sounds like a great project for a talented programmer!
The closest you could get right now might be using an X-surf card and putting a Compact Flash card on the IDE port with the drivers and the StartupSequence. It would really be booting off the CF, but would then pull all other files from the network (assuming the X-surf IDE is bootable, which it may not be).
