To access Windows 8 Charm bar with your mouse, you have to move the cursor to either top right or bottom right corner. It may not very convenient when you have a large screen. Here is a little app called Win8CharmsGesture that lets you to bring out the Charm bar with a simple mouse gesture.
It’s a free portable tool that once it’s running, it monitors your mouse movement. When it detects the designated gesture, it fires up the command to call out the charm bar. Quickly move the cursor bump to the right board of your screen twice and you will see the Charm bar pops up charmingly.
If you like the app, you can set it to run automatically on Windows Startup from the settings screen which you can call up from the system tray.
When you launch it you may be prompted by the UAC screen. You can click on More Info and click Run Anyway to bypass it.
Tip my hat to Into Windows for sharing it.