I've found some time to implement m-obex protocol based on documentation provided by samsyncro project. However I don't have any phone to test it, so any testers are welcome :-).
The testing should be quite easy - just get current Git version of Gammu (either using git or use snapshots) and try to use commands which manipulate with contacts and calendar:
gammu getallmemory ME gammu getallcalendar gammu getmemory ME 1 gammu getcalendar 1 gammu addnew test.vcf gammu addnew test.vcs
In case you have not yet used Gammu with your phone, the configuration for USB cable should look like:
[gammu] device = /dev/ttyACM0 connection = at
And for Bluetooth:
[gammu] device = address of the phone connection = blueobex model = mobex
Of course there is no guarantee that any of the commands will work, because all I could verify is that code compiles and looks correct. It might as well do something bad to your phone, so backup is recommended.