I am installing a Kramer Sierra Video 1616v3xl Matrix unit which does not have IR.
I am a little new to RS-232 Control.
It does have an RS232 port on the back which does have commands in manual.
Manual can be found here.
[Link: sierravideo.com]

I also have 8 Directv Receivers and 5 Cable Receivers that I would like to be controlled independently with the remote as well.

I would like to know the easiest and cheapest way that I can get this unit controlled through a remote such as a Logitech Harmony or other programmable IR Remote.
Which remote system would be a good fit for this system?

Any help would be greatly appreciated.

I'm happy to help you with the RS232 protocol for Kramer, but, how are you going to control the Kramer using an IR remote?

I would suggest contacting a professional AV installer to supply /install and commission the system - with a control system not based on a domestic product....