Switching shift and caps lock - heavy attack

I'd like to switch shift and caps lock pretty much globally for the game. I have arthritis which reduces mobility in my hands and it's super hard for me to reach L shift while also using W (yes it's stupid and annoying, but it's joint damage, it's not like I can just reverse it). Switching walk and sprint was no problem but I cant figure out how to bind heavy attack to caps lock + L mouse, trying to press them at the same time only binds one of the inputs. Is it possible to make my own combination keybinds?