When I looked into adding rear remotes to my Sc2400, I ended up locating a service manual for a Sc2450 and tracing how they integrated the line for the backhoe. I'm sure there are others who can chime in and tell you if this is right or wrong, but since the SX series can also be had with a backhoe, I'd try to find the service manual and find the line that would normally be used to power the backhoe hydraulics and tap into that. Thats step one...
Now, the line for the backhoe needs to be connected at all times when the backhoe is not connected. That is important. In the case of my 2400, it's essentially a return line from the SCV for the loader. So, to add a rear remote, you'll need an open center valve and tap into the line that normally feeds the backhoe. I believe with a open center 3 position valve, you'd get what I would consider one "set" of "typical" rear remotes.
I haven't actually taken the plunge on my 2400 since I currently have no use for rear remotes (was actually looking more at power beyond for grapple)... But, looking at it, it doesn't look like it would be rocket science as long as you are somewhat handy.
I feel like cub cadet should offer a power beyond kit for the smaller tractors... They have a kit for the EX series. Why not make something available for the folks who have a need for a smaller machine?