This is the tool for the 512, 1 meg and 2 meg players.
on the global Iriver site, Iriver N.A. doesn't tell you you can change the firmware. Contact Iriver and ask for the exactly similar too; for your player and how to convert your player from MTP to UMS. NOTE: U will lose all current content on the player if you convert and won't be able to play any of your purchased content even if you back it up and reload it.
Another note: They may say you can't and try to stonewall you, but if they player is sold in Europe, it can be run as Universal Mass Storage.