WARNING: Not compatible with Recent Firmwares!!!!!!!!
Hello everyone,
after some trial and error I put together a set of scripts for automatic USB networking.
What is does:
It installs a udev rule that starts up usb networking, a dhcp-daemon (included in busybox) and dropbear (from sergeys KoboLauncher) when you connect USB to a PC.
The DHCP seems to be a bit flaky on Win7, so you might have to "repair" you connection if it doesn't give you an IP (range is 192.168.142.x)
If you dismiss the connection dialog, USBnet stays connected.
If you decide to go the mass storage way, it will shut off the usb networking and load the usb mass storage, just like normal.
For this to work I had to patch the "usb"-script in /usr/local/Kobo/udev.
This is the only really critical step in the automatic setup process, because it might break usb mass storage functionality if the patch goes wrong.
Remedy #1 is to rename/remove /etc/udev/rules.d/usbnet.rules which basically disables the whole shebang.
Remedy #2 is to ssh into the kobo and fix /usr/local/Kobo/udev/usb
Remedy #3 is to do a factory reset

If you disconnect the USB it will unload the network modules and stop dropbear and the dhcp-daemon so there shouldn't be any performance impact once disconnected.
For SFTP access the binary is located in /usr/sbin
To install, unpack KoboRoot.tgz from autousbnet.tar and copy it to .kobo as usual.
Download from
dropbox
In theory this should work for all recent kobos (Mini/Touch (new and old)/Glo/Aura/AuraHD) but I could only test it with my KT N905B.
As Always:
This could potentially brick your device. If you're not ready to do a factory reset, don't use this!!!
Confirmed working on:
Touch (N905B)
AuraHD
Glo
Regards
Aydan
PS: I forgot to mention that the IP of the Kobo is 192.168.142.1
Edit: Added dropbox folder for downloads
Edit: v2 with alternate busybox binary for firmwares without native udhcpd support