How/where do I reassign the brush blending mode keyboard shortcut to a different key?

Hi, 
I would like to be able to bind a single key changing the brush blending mode from "normal" to "clear" and back because it makes for a better eraser than  the eraser tool .  It has the advantage that the  brush settings fit the rest of my painting.
I can't find where I can change the key-binding for the brush blending mode in the menu for keyboard shortcuts.
ideally I want to bind it to the c-key because that's the way I am used to it from CSP.
alternatively I'd also be okay with the Eraser automatically (i.e. without me having to set it up manually every time) copying the brush setting of the last brush I used.

I've read that the ~key would work to change brush modes, but that doesn't seem to work with my non-American keyboard (I tried pressing altgr and + key , which would be depicting the ~ key in writing, but it doesn't work as a shortcut, PS doesn't react on it). as it is it's faster to go off my painting, press on the drop down menu and change brush mode and then go back to painting....every 5-10 seconds roughly.
that's just extremely inconvenient for a tool I use atleast 40% of my painting process.
it makes the painting process a lot more cumbersome compared to other apps that have the ability to change the brush blending mode with a single key press.