Comment 41 for bug 885027

Why do you really want to handle the auto-mounting part by yourself? I mean, if udisks (or other) is not available, the user will probably know how to mount a removable device by his own without needing the help of any helper tool, every desktop linux user should know how to mount a removable device on his distro (whether it's done automatically, through a file manager or by using mount as root).
And if you really want to mount a device through calibre, you can call mount using gksu which will warn the user that your program require root access and will ask for it (and so the user will be able to check if the command being run is not dangerous).

The best way will be to have a script (without suid!) that first check for all available mounting tools (udisks, pmount,....) and fall back to gksu mount.

Because if system doesn't provide a tool to allow mounting device for regular user, it can simply means that this user is not allowed to mount the device, and that's not the role of your program to decide whether it should be allowed or not !