Just for the record: The EM7345 use USB class functions exclusively, and does not need any device specific driver under Linux. It is supported by the standard cdc_acm and cdc_mbim drivers. Both are included with the current Debian stable release (jessie).
Enabling the GPS function probably depends on vendor specific AT commands. The device use an Intel (formerly Infineon) chipset, so you might have some luck looking for generic Intel/Infineon instructions if Lenovo doesn’t provide docs. Or you can snoop on the WIndows applications if Lenovo enable the GPS in Windows. I recommend USBPcap for USB snooping under Windows.