How do I make Portal (steam) work with X360CE?

I ran the 32-bit version of x360ce.exe in both C:\Program Files (x86)\Steam\steamapps\common\Portal and C:\Program Files (x86)\Steam\steamapps\common\Portal\bin. It created the xinput1_3.dll file in both directories. I fiddled with the permissions of the DLL in the bin directory to prevent it from being overwritten by the game.

No matter what I do, Portal refuses to recognize the controller (though X360CE does).

The controller is a Logitech Rumblepad 2.

Just use the controller configuration tool that is built into Steam. So far it allowed me to play any game that only allows XInput controllers with my Logitech Rumblepad 2. Here's a tutorial on how to set it up: https://www.howtogeek.com/234427/how-to-remap-buttons-on-your-steam-controller/