Maybe try setting both of them to keyboard buttons with Xpadder, and then setting those keyboard buttons to what you want in dolphin. You may have to check "enable background input" for this to work, but you may not.
OS: Windows 10 64 bit Professional
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
