Hi Jeff. When you open the EZ mixer I believe in the upper left there is a drop down box. Select multi channel. On the lower portion of the mixer you can also assign specfic tracks to specific drums. Track 1 = kick, 2 = snare and so on.
I believe this is what your asking for. However, I also have the Latin Percussion kit, and you have to assign your specific roland pads to it. The way I did it was to open the kit so that I'm viewing it, then on your TD4 module go to assign note. You will see that as you select different midi notes on the module that it will control different parts of the latin percussion kit. When your finished assigning the midi notes, save it.
I actually have saved kit 2 on my td so that it controls my Latin percussion kit. Kit one controls my Nashville kit and so on.
Hopefully this helps you.