LightDM - Oct 2015 - multiseat setting correctly keyboard layout

hello,

I have a working multiseat desktop, I just have a slight issue with it
: one of my keyboard has a uk layout, seat0 and that's the default for
the system, the other seat1 has a french keyboard.
before 1.15 I think I used to have a xorg.seat1.conf that contained :

Section "InputDevice"
        Identifier      "Keyboard1"
        Driver          "evdev"
        Option          "Device"
"/dev/input/by-id/usb-Dell_Dell_QuietKey_Keyboard-event-kbd"
        Option          "XkbLayout"     "fr"
EndSection

with loginctl now in charge of adding keyboards to appropriate seat, I
don't know whhare I could specify that.

➜  ~  loginctl seat-status seat1
seat1
        Sessions: *c2
         Devices:
                  ├─/sys/devices/pci0000:00/0000:00:03.0/0000:02:00.0
                  │ [MASTER] pci:0000:02:00.0

├─/sys/devices/pci0000:00/0000:00:03.0/0000:02:00.1/sound/card2
                  │ sound:card2 "HDMI_1"
                  │
├─/sys/devices/pci0000:00/0000:00:03.0/0000:02:00.1/sound/card2/input16
                  │ │ input:input16 "HDA ATI HDMI HDMI/DP,pcm=3"
                  │
├─/sys/devices/pci0000:00/0000:00:03.0/0000:02:00.1/sound/card2/input17
                  │ │ input:input17 "HDA ATI HDMI HDMI/DP,pcm=7"
                  │
├─/sys/devices/pci0000:00/0000:00:03.0/0000:02:00.1/sound/card2/input18
                  │ │ input:input18 "HDA ATI HDMI HDMI/DP,pcm=8"
                  │
├─/sys/devices/pci0000:00/0000:00:03.0/0000:02:00.1/sound/card2/input19
                  │ │ input:input19 "HDA ATI HDMI HDMI/DP,pcm=9"
                  │
├─/sys/devices/pci0000:00/0000:00:03.0/0000:02:00.1/sound/card2/input20
                  │ │ input:input20 "HDA ATI HDMI HDMI/DP,pcm=10"
                  │
└─/sys/devices/pci0000:00/0000:00:03.0/0000:02:00.1/sound/card2/input21
                  │   input:input21 "HDA ATI HDMI HDMI/DP,pcm=11"

├─/sys/devices/pci0000:00/0000:00:1d.2/usb8/8-1/8-1:1.0/0003:413C:2106.0002/input/input3
                  │ input:input3 "Dell Dell QuietKey Keyboard"

└─/sys/devices/pci0000:00/0000:00:1d.2/usb8/8-2/8-2:1.0/0003:046D:C063.0004/input/input5
                    input:input5 "DELL DELL USB Laser Mouse"

thanks for any pointers :)

benoit