@vve,
Yes I will use that driver set. Thanks.
I'm analysing the drivers and will use them. Report soon.
However, I've to hack them as they don't include yet the new vid/pid.
Try
VID:
12D1,
PID:
1568 in Google 
!
This is the reason why I need to know wich drivers are being used during the update process.
Up to now, everything is OK, but I'm loosing the com ports as soon as the HF switches to update mode.
The modem returns to the Win8 MBIM configuration with another vid/pid.
This is a totally new modem mode ! Very easy with Win8, very annoying with other OS
!
It's really difficult to switch it to the standard Win7 or older mode.
I suppose HF will use these drivers during the update :
ew_hwupgrade.sys
w_hwusbdev.sys
But perhaps others ?
Regards
Yves