I agree with Caleb, although if you want to control multiple volume levels or other parameters of the DM84 it is an option.
Crestron, along with AMX and Extron, try to limit availability of hardware to authorized dealers and software to authorized programmers. It's a way to help insure some level of quality and competency in order to both offer a better end product and control the support required.
I used to do a lot of AMX and Crestron programming back in the days of AXCESS and SIMPL-C. I was providing some ongoing programming for a major corporate client when they decided they had a number of computer programmers in-house and would do it themselves. They were soon back, noting that the programming was essentially a specialized language. Things have progressed since then but control system programming still requires some specialized knowledge.