Make USBLan mode permanent?

[wolfy]

I set up a telnet connection to my phone, and I can switch into this mode either with a script or with "usbmode" (a very good utility), but unfortunately both ways are not permanent when switching the phone off - I'd like to have this mode enabled when rebooting, because I've read that I can potentially unbrick the phone when e.g. a corrupt ezx-theme freezes the boot process, in which case I could overwrite the responsible theme with the default theme if I only had a telnet session. That way, I wouldn't have to flash the phone when a theme install and subsequent reboot should go wrong.

### UPDATE ###
I should mention that sending the "AT+mode=99" sequence does NOT work on my phone (this seems a common "feature" of all german versions - it's really almost funny that motorola seems to introduce different quirks into each and every version for different parts of the world...)
If this could be changed, that would solve my problem, because I could always activate USBLan-mode even after the phone has been rebootet.
So if anyone knows if this is a hardware or a firmware issue...?
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So, how do I make the USBLan-mode peranent? Or more generally speaking, is there a possibility to execute .lin-files on startup?
BTW, the USB mode selected in "Setup" seems to be permanent, so one would just need to keep it on "Modem" and execute said script on boot-up to switch into USBLan-mode.

If anyone should wonder about this script (I dug it up somewhere), here it is:

File "usblan.lin"
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#!/bin/bash
echo MotNet > /proc/usbd-switch
ifconfig usb0 up 192.168.1.2 netmask 255.255.255.0 mtu 900
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The IP can be assigned arbitrarily in the 192.168.1.X range, the MTU is set quite conservative, because 1500 seemingly yields problems under certain conditions.
And of course LinLoader is needed to execute this.