uncomment the otg_host line on <system>/etc/vold.fstab. It should look like this:
#used for usb otg host
dev_mount udisk /mnt/sdcard/udisk auto /devices/platform/fsl-ehci.0/usb
When you plug usb stick, it is automaticaly mounted.
To umount usb stick, please go to settings > storage > umount udisk
