Enable this on init.recovery.usb.rc

write /config/usb_gadget/g1/functions/mass_storage.0/lun.0/file "/dev/block/sda25"
write /config/usb_gadget/g1/functions/mass_storage.0/lun.1/file "/dev/block/sda26"
write /config/usb_gadget/g1/functions/mass_storage.0/lun.1/cdrom "0"
write /config/usb_gadget/g1/functions/mass_storage.0/lun.0/cdrom "0"
symlink /config/usb_gadget/g1/functions/mass_storage.0 /config/usb_gadget/g1/configs/b.1/f3