@Capsia Thank You! I'll continue searching but now with proper tools. For more advanced users maybe this or this will help - Especially this part of article: "Here is an example script of modem initialization:(...)"

@doniks its just a .img file contained in a .gz just extract the .gz file and flash the resulting image onto a USB drive (or a harddrive depending on if you'd wanna install it as main os)

@ali461 you're welcome!