Adding custom drive icons

[Andreas Heinlein <aheinlein gmx com>]

Hello,

does anyone know how nautilus chooses which icon to display on the
desktop for which type of drive? I mean there are several different
icons for hard drives, removable drives, LUKS-encrypted volumes and so
on. I want to add an icon for TrueCrypt volumes, which are currently
shown like hard-drives.

I do not want to add an icon for a specific volume, I could do that with
a personal customized icon. I want to add an icon for all future volumes
of a specific type.

Is that possible?

Thanks,
Andreas