The first tip is: do not
update your kernel to one of mine
... or to any kernel based on recent mainline code.
I know that Albert (aaribaud) is also very interested in USB mass storage device support; it was his main reason for buying an EDmini v2
A prerequisite for this is obviously support for the USB device (slave) port.
Unfortunately Marvell have not introduced USB device support into the mainline kernel so it is only currently supported on the stock LaCie kernels.
Albert or I intend to ask Marvell to add this support, which was present in the Marvell development kit LaCie used for their stock kernel.
We looked at forward porting this code to mainline ourselves but it seems far from trivial and there is the possibility of the result being NACKed by Marvell