REFERENCE
To enable extended accelerators for the Bookmark bar:
1. Choose File - Preferences - User Preferences.
2. Select Basics.
3. In the Additional Options box, select "Show extended accelerators" and then click OK.
To use extended accelerator keys in the Bookmark bar
After you enable extended accelerator keys, press ALT+B to display them in the Bookmark bar. You can use the accelerator keys as follows:
To use extended accelerator keys in window tabs
To use an accelerator key, press ALT+W, followed by the number that appears next to the window tab.