If you've dabbled with LUA via FSUIPC you can control the (standalone, at least) CaptainSim WX radar by this route.

For example I have a script file named wx_rdr_on.lua with the following line:

ipc.writeLvar("L:Wxr_ModeSwitch1",3)

Script file wx_rdr_off.lua has this line:

ipc.writeLvar("L:Wxr_ModeSwitch1",0)

I've used FSUIPC to assign keystrokes to run these short scripts, and I have a voice-control add-on that lets me tell my FO to turn the CaptainSim WX radar on and off.

The other CaptainSim WX radar controls are also accessible via LUA as well, although I've not implemented key mapping yet:

L:Wxr_RangeInc=0
L:Wxr_RangeDec=0
L:Wxr_TiltKnob=0

etc.

I don't think I'm that good with using FSUIPC so if I can do it, I'd think most anyone could.  

Hope this helps,