You can assign the shortcut to any key that you want.
Keyboard shortcuts are one of the most powerful features of FCP, and one of the least discussed. By not using default shortcuts and instead configuring my keyboard to my own style of working, I was able to edit about 3 times faster than before. (Those FCP custom keyboards with pre-marked keys look cool, but will strike you as a totally dumb idea once you realize how to set shortcuts.)
Play with the keyboard setup option (Tools > Keyboard Layout > Customize) and also note that you can search for the effect you want to assign to a key. The tricky part is in knowing what the effects are named!
Default settings are thus: Add Audio Transition is CMD-Opt-T, which is stupid. And Audio Favorite 1 is Ctrl-Shift-3. Also stupid. I use the letter Y for that first shortcut. That's it. I set any most-used option to shortcuts that don't require a 2nd keystroke to activate, and keep the 10 or so most-used options in spots where I don't need to move my hand to reach them.
One more trick: If you ever have to use a different copy of FCP on somebody else's computer, e-mail yourself your FCP keyboard shortcut pref file form your own machine first, and open it on the new machine -- voila -- no messing around with somebody else's work setup.