That’s a description of PID switching, which the OP obviously know how to do (referring to AT!UDPID). The request was for VID switching.
My guess is that is no documented way to do this. It is probably part of the device specific programming, like the IMEI number etc. And although I don’t really know, I do wonder if Sierra Wireless maybe actively use their 3(?) different VIDs to identify different modules sharing the same PIDs (68a2/68a3):
0f3d:68a2 - MC7700 in QMI mode
0f3d:68a3 - MC7700 in DirectIP mode
1199:68a2 - MC7710 in QMI mode
1199:68a3 - MC7710 in DirectIP mode
114f:68a2 - MC7750 in QMI mode
114f:68a3 - MC7750 in DirectIP mode
But I don’t know if this guess is correct or not. Confirmations or corrections are welcome.
In any case, there is absolutely no way you can change a MC7700 module into a MC7710 module. The differences are more than just a VID. Therefore I don’t understand the original request. What possible benefit is there changing the VID? Hmm, maybe fooling a BIOS whitelist? Yes, that could be a valid reason.
EDITed: fixed stupid VID/PID typo…