Normal this works by pressing the ALT-key, then the chars with the ampersand gets underlined. (Like with XY main menu)
But the CTB-menus are closed while pressing the ALT-key. That was maybe overlooked by Don?
As an tip to see that the ampersand basically works you can press and hold the ALT-key first, and click then the button.
You will see an warning dialog and after OKing them you see the mnemonics
Maybe use an work around like this:
"(&B)readcrumb|icons\breadcrumb.ico" #525;
"(&S)hortcuts|icons\shortcut.ico"
"(&R)ecent Loc|:mru" button "mru";
"(&H)otlist|:hotlist" button "hotlist";
Ahh, btw, you know that you can jump to the first char of each menu item by just pressing that leading char, even without any ampersand used?
All you have to do after this is pressing the enter key too.
This works even if more items have the same beginning char.