RIFF Box Firmware v1.45
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– Added MassStorage Mode for RIFFBOX2

RIFF JTAG Manager v1.69
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– Fixed the bug for General Purpose Partition Sizes
– Added feature to switch ON/OFF the MassStorage Mode. For this, please connect an eMMC (either via Direct or ISP interface),
make sure it is detected (on the “eMMC/SD Card” page), and on the ‘eMMC/SD Advanced’ dialog click the ‘MassStorage Mode ON/OFF’ button to setup which partitions are to be mounted.
Please note, for stable connection, first of all do reads on the “eMMC/SD Card” page to adjust stable Frequency, BusWidth and Voltage.
After you click “MassStorage Mode ON/OFF” button, current settings for Voltage, Frequency, Bus Width will be written into RIFFBOX non-volatile memory,
and while the MassStorage mode is ON, upon each connection to USB the RIFFBOX will additionally to normal Control interface enumerate the MassStorage Disks (as if a Flash Stick is connected to PC)

eMMC Partition Table FullFlash Image Files Processing Plugin (eMMCDiskPartitions.dll) v3.02
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– Added support for User Area Partition bounds selection from the JTAG Manager’s MassStorage settings dialog
– Added file system detection: the plugin analyzes the partition’s data structure to autodetect what file system (if any) is used. The result is displayed in the new “F/S” row
..

To mount EXT/x partitions You should install EXT FS driver from here:

http://www.ext2fsd.com

You can read more details at official support forum:
http://www.unlockforum.com/showthread.php/riff-box-firmware-v1-45-riff-jtag-manager-31615.html