Presuming you mean a keyboard shortcut to invoke Chrome:
1. Gain focus on the Chrome Shortcut.
2. Bring up the context menu, choose Properties.
3. Navigate to Shortcut key box, then hold down CTRL or ALT (which will give you CTRL+ALT as the start of the shortcut, no matter which you are holding), and follow with the character you wish to use in conjunction with CTRL+ALT for the shortcut.
The fast way through all but the selection of the character is once the context menu is up, hit R (Properties) followed by ALT+K (jump to shortcut key edit box), then pick up at "hold down CTRL or ALT . . ."
Brian - Windows 10 Pro, 64-Bit, Version 1809, Build 17763