Grâce à tes conseils je suis presque arrivé à mes fins....
Si je passe simplement la commande
$ sudo eject /dev/sr1
et aucune autre commande voici ce que j'obtiens dans la /var/log/messages
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Aug 12 01:04:08 lx-didier-portable kernel: end_request: I/O error, dev sr1, sector 83840
Aug 12 01:04:08 lx-didier-portable kernel: sr 2:0:0:0: [sr1] <6>usb 5-1: USB disconnect, address 2
Aug 12 01:04:08 lx-didier-portable kernel: Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK,SUGGEST_OK
Aug 12 01:04:08 lx-didier-portable kernel: end_request: I/O error, dev sr1, sector 83952
Aug 12 01:04:08 lx-didier-portable kernel: scsi 2:0:0:0: rejecting I/O to dead device <====== Après l'éject
Aug 12 01:04:08 lx-didier-portable kernel: scsi 2:0:0:0: rejecting I/O to dead device
Aug 12 01:04:08 lx-didier-portable kernel: scsi 2:0:0:0: rejecting I/O to dead device
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Aug 12 01:04:08 lx-didier-portable kernel: scsi 2:0:0:0: rejecting I/O to dead device
Aug 12 01:04:08 lx-didier-portable kernel: scsi 2:0:0:0: rejecting I/O to dead device
Aug 12 01:04:08 lx-didier-portable kernel: scsi 2:0:0:0: rejecting I/O to dead device
Aug 12 01:04:09 lx-didier-portable kernel: hub 1-0:1.0: unable to enumerate USB device on port 7
Aug 12 01:04:09 lx-didier-portable kernel: usb 5-1: new full speed USB device using uhci_hcd and address 3
Aug 12 01:04:10 lx-didier-portable kernel: usb 5-1: configuration #1 chosen from 1 choice
Aug 12 01:04:10 lx-didier-portable kernel: usb 5-1: New USB device found, idVendor=1410, idProduct=4400
Aug 12 01:04:10 lx-didier-portable kernel: usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=4
Aug 12 01:04:10 lx-didier-portable kernel: usb 5-1: Product: Novatel Wireless HSUPA Modem
Aug 12 01:04:10 lx-didier-portable kernel: usb 5-1: Manufacturer: Novatel Wireless
Aug 12 01:04:10 lx-didier-portable kernel: usb 5-1: SerialNumber: 0123456789
Aug 12 01:04:10 lx-didier-portable kernel: usbcore: registered new interface driver usbserial
Aug 12 01:04:10 lx-didier-portable kernel: drivers/usb/serial/usb-serial.c: USB Serial support registered for generic
Aug 12 01:04:10 lx-didier-portable kernel: usbcore: registered new interface driver usbserial_generic
Aug 12 01:04:10 lx-didier-portable kernel: drivers/usb/serial/usb-serial.c: USB Serial Driver core
Aug 12 01:04:10 lx-didier-portable kernel: drivers/usb/serial/usb-serial.c: USB Serial support registered for GSM modem (1-port)
Aug 12 01:04:10 lx-didier-portable kernel: option 5-1:1.0: GSM modem (1-port) converter detected
Aug 12 01:04:10 lx-didier-portable kernel: usb 5-1: GSM modem (1-port) converter now attached to ttyUSB0
Aug 12 01:04:10 lx-didier-portable kernel: option 5-1:1.1: GSM modem (1-port) converter detected
Aug 12 01:04:10 lx-didier-portable kernel: usb 5-1: GSM modem (1-port) converter now attached to ttyUSB1
Aug 12 01:04:10 lx-didier-portable kernel: usbcore: registered new interface driver option
Aug 12 01:04:10 lx-didier-portable kernel: drivers/usb/serial/option.c: USB Driver for GSM modems: v0.7.1
Aug 12 01:04:10 lx-didier-portable NetworkManager: <info> ttyUSB0: Device is fully-supported using driver 'option'.
Aug 12 01:04:10 lx-didier-portable NetworkManager: <info> Found new Modem device 'ttyUSB0'.
Fin de l'acte 1, mon dongle est reconnu par le kernel et par NetworkManager.
A ce stade je devrais donc pouvoir me connecter par NetworkManager...
En attendant un patch pour la reconnaissance de l'ID 1410:5010 ça devrait donc pouvoir le faire...