if you don't own a serial cable, then you'll not be able to do it in one go but rather you'll need to follow a couple steps:
- flash your modified ( starting /etc/telnetd_start.sh from within /mtd_exe/rc.local ) exe.img
- access you device via telnet and create your required start-up script in /mtd_rwarea
- modify your exe.img a second time to now rather invoke your /mtd_rwarea/my_startup_script
Normally the /mtd_rwarea space is not erased after flashing the FW.
This was due to a typo. The binary is called "bml.restore" and you'll for sure have it. However you really need to be very careful. Currently only flash the same version of exe.img using this method, as e.g. flashing a newer FW version ( e.g. the new 2009 version ) somehow seems to cause major problems.So then I tried to modify just the exe.img and flash it manually however I do not have bml.resore so I cannot do it that way.
Alternatively you could also have a look at following posting, which shows a new way to enable the telnetd, entirely without the need to flash the FW.
Regards
dynamic