Hello there! I have recently discovered how to play almost every C&C game with a controller via steam.
Here's a tutorial that explains better than i can on how to add Non-steam games to your steam library: https://support.steampowered.com/kb_article.php?Refinery=2219-YDJV-5557
(Notice: You cant use the w3d hub launcher to play, you have to go and find that game in w3d's files. (You may have to do this with other C&Cs too.))
After that you will have to turn on big picture mode, via the view part on steam.
Then go to the library and find the game, here is when you can map the controls to how you like. After that you are finally able to play almost every C&C on contoller.