Hey everyone,
I just discovered CnCNet and was able to come up with a possible solution using the tips from above. It's not perfect, but it might help some. FWIW, I got this to work on High Sierra 10.13.1. Alright here we go...
Right click "CnCNet" --> Show Package Contents --> Open Wineskin.app
Select "Set Screen Options"
Set "Override Wine control of Screen Settings" to "Override"
Deselect "Use Mac Driver instead of X11"
Select "Decorate Windows", "Auto Detect GPU Info for Direct3D", "Use Direct3D Boost" (not sure if these matter, but I have them selected)
Set "Override Settings" to "Rootless (windowed)"
Select "Virtual Desktop at" and choose a resolution/size for your window.
Set Installer Options to "Force normal windows"
Exit Screen Options
Quit Wineskin
Launch CnCNet.
Select "Settings" And set the game resolution to same resolution from Wineskin
Set the Renderer to "ddwrapper"
Set Display Mode to "Fullscreen"
Like I said, it's not perfect and some of the menus are cut off at certain resolutions, but gameplay is pretty solid. I hope this helps.