Oh man, this always happens! I meant to get in some studying for my OS midterm tomorrow, and I spent.. just too much time.. trying to get my phone to recreate the Babylon 5 doorbell sound when I get text messages :P
Getting a sound onto the VX4400 was actually not that hard. 16khz 16kbps mp3 format did the trick. Change the file extension to .mid, and upload with bitpim.
The hard part seems to be getting it to the right volume. My properly normalized file clipped really hard. I stopped playing around with this before I came to a solution, but I think linealy scaling it down to 0.1-0.2 is where it should be. Except then I worry that it'll be too quiet to hear!