Assign shortcut keys to menu items?

Is there a way to assign shortcut keys to menu items such as “Search in Google”? It would be great to be able to look something up just by highlighting it and hitting a key or key combination. The right-click method on a Macbook to make this particular menu selection is pretty awkward (the two-finger click), if you’re otherwise using the keyboard to highlight the word (by pressing Alt-Shift-Left arrow right after writing the word).

I’ve tried assigning this using the OS X keyboard preferences, but no luck. In the old days of OS 9 one could do some ResEdit hacking to assign keys to menu items, but I haven’t had the need for it since (and doing so might be in breach of the license agreement so don’t try this at home kids).

This probably has something to do with the fact that the Search in Google menu item is a system level thing, available in many applications. I tried adding one for “All Applications”, but that didn’t work for me either.