> This is kind of complex configuration.
>
> Pcmcia > usb 2 > ide > dvd 5.25 drive.
>
> I write cd, dvd but I cannot spin down (lower speed) the device
> in reading.
>
> Compiled setcd-1.5 from debian, I get info from the drive,
> but still is in fast mode.
>
> I also have sdparm, suppose that hdparm is useless in usb
> devices. USB connected devices are treated like scsi, right?

readcd dev=/dev/sr0 sectors=0-1 speed=4
try