Originally Posted by Thom Little
Connect the Bionic to your PC using the USB cable that came with it.
There will be two devices displayed by File Manager when looking at Computer on the PC.
Create a folder on the SD or SD-Ext ... ringtones ... I chose /media/ringtones
Copy the MP3 files to the ringtones folder
Disconnect the Bionic from the PC (so the Bionic Adds can access the SD card)
The ringones are now available in the various dropdown lists of ringtones.
This also works with /notifications!