One way to do it would be to alert the user with a unobtrusive notification somewhere on the page that says "hey, we've added some keyboard shortcuts for your convenience".(I've found the top center to be the best place to do this in my experience).
In this specific example, the text says "Did you know you could use keyboard shortcuts in this app? Go ahead, hit Alt and see what happens." Check the visual below.
Note that I've added a close button in the notifier section to let the user dismiss the alert. And if necessary, you can even add the "Don't show again" option in there.
And once the user hits "Alt", you can show the keyboard shortcuts overlaid on top of the controls they apply to. In your example, if they apply to an accordion control, display the tips on top that control.
In the visual below, I've displayed "Ctrl + t" on top of the Campfire image.
Once the user hits "Alt" and sees the tips above, you can change the text on the alert notifier to indicate that they can hit "Alt" again to dismiss the tool tip text. I've changed the background color of the alert to make sure the user notices that the text in it has changed.
This way the app offers helpful tips (no pun intended) but the tips themselves are unobtrusive to the user causing little resistance.
Hope that helps.