How can I change the keyboard shortcut for switching tabs in Mac Terminal?

Before Sierra (El Capitan and earlier),

You can change key bindings for almost all Cocoa apps in System Preferences, including Terminal.app.

Go to System Preferences > Keyboard > Shortcuts > App Shortcuts, then add a new shortcut for Terminal (located in /Applications/Utilities).

1: Install SIMBL (plugin enabler): http://www.culater.net/software/SIMBL/SIMBL.php

2: Install the TerminalTabSwitching.bundle

git clone https://github.com/dabeeeenster/terminaltabswitching
cp -r terminaltabswitching/TerminalTabSwitching.bundle "/Library/Application Support/SIMBL/Plugins"

3: Restart the Terminal app, and enjoy Cmd+[0-9] tab-switching.

FYI: If something like plugin is not verified in terminal version # (a number) appears when you open your terminal again, maybe the following information can help.

(1) Open

/Library/Application\ Support/SIMBL/Plugins/Terminal/TerminalTabSwitching.bundle/Contents/Info.plist

using your favorite text editor under sudo.

(2) Search For <key>MaxBundleVersion</key>.

(3) Change <string>280</string> at next line to your terminal version number or higher like <string>300</string>. Save.

(4) Quit terminal and reopen it. Hopefully that prompt would disappear and you can use Cmd+[0:9] for tab switching.