How do you use the MT3 converter to convert a Legend of Zelda midi file into calc format. Or TruSound.

For MT3, there is an online converter which requires MIDI files and will output the 8XP file that you can directly send to your calc. Here is a link to that
As for trusound, the steps are described in the readme, but here is a quick summary:

1. Find the sample rate that TRUSPEED returns (if you get this wrong, the song will either play a little too fast or a little too slow).
   
2. Convert the song you want to an 8 or 16 bit wav file with the sampling rate determined above (I like to use Audacity) and place it in the folder called "wav".
   
3. Use the command prompt to call the included "convert.bat" file, passing what you want the program to be named as an argument.
   
4. The output file should be in the folder called "8xk".

With trusound, you just need to make sure that you aren't going over the amount of memory available on your calc, which is not super easy to do given how large music is compared to the amount of memory available on calcs.