i dont really know what tethered means so i can't answer that. all i did was made it so my microSD shows up as a removable and thats it and connect it to my PC thru the usb to power it and transfer music.
when its like that the phone will not ring, and i have searched to try and adjust a setting or something but it wont work.
i have my storm set to prompt me on mass media .. because if your ringtones are stored on the media card, they will not play while in mass media mode.
i usually only turn mass media on to transfer stuff to my phone, then unplug, plug back in, hit no when the mass media prompt comes up, and charge it that way.