There's a couple things that you're missing here.
my problem is that I can ONLY make ONE instance of DimPro, where I can make as many instances of my Alesis, on as many different channels as I want.
There are four little icons to the left of the DIMENSIONPRO logo. Click the second one from the left (looks like a syringe). Check Set Program as Multitimbral, then click OK. This setting is saved with the .prog file.
For notes C3, D3 I wanted to use 1 instance of DimPro (DimPro 1) using the patch called Assorted Kicks and Snares (something named like that)
Forget the 'patch' part. You don't want to use the Program Browser. That overwrites all four Elements; even if they're initialized and empty of all settings. An instance is four complete synths [Elements - .elem file]; mixed together with effects and a patch bay as a combi [Program - .prog file]. The core 'oscillators' are .wav files and collections of .wav files (.sfz).
Instead, make sure that you're in Element 1 [E1 lit]. Click on the Multisample slot below it, and load the core .sfz file. Most of the drums are in the 02 - Drums subfolder. I'm guessing that you meant the accoustic
(sic) bd & sd.sfz here.
... then use DimPro 2 for Assorted Toms (white notes F3-C4), ...
Click on E2, click on the Multisample slot, and load multi toms.sfz.
... DimPro 3 for Cymbals.
Click on E3, click on its Multisample slot, and load stereo cymbals super kit.sfz. For ****s & giggles, click on E4, click on its Multisample slot, and load another kit in .sfz format.
Now
save the program as something (King Conga Drum.prog).
Now, on the DimPro 1 (Assorted Kicks & Snares) I would assign say, a C3(36)INPUT note to F5(46 I think)OUTPUT for my Kick, or note assignments for snare.
Go to the Drum Map Manager. Reassign the input and output notes any way that you want. Just make sure that the kicks and snares are output to Channel 1, the toms to Channel 2, the cymbals to Channel 3, and whatever to Channel 4.
And - of course - the Drum Map Manager has to 'Out Port' to your new 4-channel multitimbral instance of Dimension Pro. One small caveat: It will be mixed down to a single set of stereo audio outputs. Cakewalk saw fit to squash the multi-out design back when the original Dimension was released. (Check out the vestigial Outputs parameter in all of the Microhosts.)
Let me know how this works out for you. This isn't theory. I do it all of the time.