I'm used to Apple laptops, on which Function + Backspace is mapped to Delete. I'm also okay with Shift + Backspace.

Is there a way to obtain this? Note, I'm using Xmonad and have some keyboard modifications set up with xmodmap but have very little understanding of how it works.

I've tried xmodmap -e "keycode 22 = BackSpace KP_Delete BackSpace BackSpace", which works in some applications but is ignored by my terminal.

I've seen this question but it seems KDE-specific. I would prefer not to have to use some GUI.