@XJIOP:
Keine Ahnung, welche Sprache Du eigentlich sprichst, Deutsch ist es wohl eher nicht, daher versuche ich es mal in Englisch - wenn das keine Option ist, gerne auch noch mal in Deutsch.
The automatic start of a telnet daemon will be done by a binary called 'telefon'. Because this doesn't exist (or is not executed) on a 3490 (afaik this model has no telephone support), it's useless to change any settings of the firmware. The only real possibility to execute a telnet daemon on such models is to start it yourself. Therefor you need a "hook" into the firmware, where the process could be started while booting the box.
The former way to upload a "pseudo image" (it's only a tar file with a script called 'install', which will be executed after uploading) isn't useful any longer, because there will be an automatic restart of the device after such an attempt and the only way to avoid such a restart, is an image prepared specially for this case, which will kill the delayed restart process in good time in advance.
But there's another problem using the "pseudo image method" ... the first step while uploading such an image is a partial shutdown of the system (many daemons will be stopped) to ensure there's enough room (in memory, where the tmpfs is residing) to process a "real update image" without hassle. If you want to use any internet connection (as I'd assume, if you want to use 'wget') after uploading such an image and starting your telnet daemon, you've to restart the dsld process first, which has been stopped while uploading the image from a local source (file upload), because it isn't necessary any longer in this case. It's not as easy to bring the whole device back to a "fully functional state" after such a partial shutdown without restarting it - after the restart your telnet daemon has gone again.
The only
reliable solution to activate a telnet daemon on a 3xxx-model (or better on every model without the 'telefon' binary) is a (permanent) modification of an original firmware image. You can find some threads here, how this can be done, but it's no task which can be finished within 10 minutes.
There
could be an
easier solution for a 3490 to modify the firmware (with only local access needed, after you've prepared an USB storage stick with the needed files), if you've got a temporary "stable" access to a shell on the device (that needs a special pseudo image, as mentioned above or any other "hack" to start a telnet daemon for the first time), but I haven't got enough information about the 3490 model to make the script work with this model too.