for kernel config,
drivers->scsi->scsi disk support
drivers->usb->usb devices filesystem, usb mass storage .
and you need vfat support as in CF drive.
This is the log of my usb host on pci,
<div class='quotetop'>QUOTE </div>
--- Quote Start ---
hub 8-0:1.0: USB hub found
hub 8-0:1.0: 2 ports detected
Initializing USB Mass Storage driver...
scsi0 : SCSI emulation for USB Mass Storage devices
usbcore: registered new driver usb-storage
USB Mass Storage support registered.
Freeing unused kernel memory: 372k freed (0x17e000 - 0x1da000)
init started: BusyBox v1.2.0-pre0 (2006.04.26-14:48+0000) multi-call binary
BusyBox v1.2.0-pre0 (2006.04.26-14:48+0000) Built-in shell (msh)
Enter 'help' for a list of built-in commands.
# Vendor: Multi Model: Flash Reader Rev: 1.00
Type: Direct-Access ANSI SCSI revision: 00
SCSI device sda: 1997312 512-byte hdwr sectors (1023 MB)
sda: assuming Write Enabled
sda: assuming drive cache: write through
SCSI device sda: 1997312 512-byte hdwr sectors (1023 MB)
sda: assuming Write Enabled
sda: assuming drive cache: write through
sda: sda1
Attached scsi removable disk sda at scsi0, channel 0, id 0, lun 0[/b]
--- Quote End ---