Running 10.6.8 on a MacBook Pro.
My goal: to have my "Caps Lock" key instead function exactly the same as the "Return/Enter" key.
The reason: I have a broken right arm and need to minimize its use for a couple months, yet still need to work on my computer -- and one of the few keys that ONLY exists on the right side of the keyboard is the "Return" key; if I can create a "Return" key on the left side of the keyboard, if would make my computer work much easier in general and more importantly much easier to do with just my left hand.
I already tried to fiddle with "Keyboard Shortcuts" in the System Preferences, but could find no way to achieve this -- the "shortcuts" always seem to require a "modifier key," which is not what I want -- I want the Caps Lock to behave exactly like a Return key all on its own, without a modifier key.
I need the left side's Shift, Tab, Function and Escape keys for other purposes, so I don't want to remap those. The only "unnecessary" key on the left side of the keyboard is the Caps Lock key, so that is specifally the key I want to re-map.
Any way to do this system-wide? And if not, any way to do it application-by-application?
I just found the solution myself, after posting this question.
I will post my answer here, to help other users.
The third-party app that allows you to remap "Caps Lock" to "Return" in 10.6.8 is called "PCKeyboard Hack," and can be found at https://pqrs.org/macosx/keyremap4macbook/pckeyboardhack.html.en#history .
You'll need to install an older version of "PCKeyboard Hack," because the newer versions are for 10.7 and later. I used version 6.3.0, which seems to be the last one made for 10.6.
I downloaded it and installed it. Restart.
THEN, before you try to use it, go to System Preferences > Keyboard > Modifier Keys button and change "Caps Lock" to "No Action." This is essential.
THEN, also in System Preferences, choose the new panel "PCKeyboard Hack" at the bottom, click on the first box which is "Change Caps Lock," and then (here's the key) click on the default keycode "51" and change it to "36," which is the keycode for "Return" on Mac keyboards, as revealed here: http://web.archive.org/web/20100501161453/http://www.classicteck.com/rbarticles/ mackeyboard.php .
Close System Preferences and give it a try -- it works!
So consider this question "answered"!