Sorry Robert, for a late respond
To configure 3Gmodems, imho, the easiest way is networkmanager, in kde now called networkmanager-plasmoid, in gnome2 nm-applet.
You get a checkbox to configure stuff for eth0, vpn, wireless and 3Gmodems, only filling in the necessary issues, like provider and telNr, saving and connecting
I remember configure 3Gmodems via yast2 in opensuse, this was related to kinternet in versions 10.x and used wvdial (still possible)
Connman and ofono I never got working, they are not available on petite-linux-cd; even the problem is, they are not in opensuse-repos - at least, I don't find them
So, if you got this to work, let me know how.
If there will be a petite12.x, also let me know, would like to check this one!
Martin