Appears to work identically to bind1, except the keybinding created also gets saved into playercfg.lua, as a "debugbindup". To deactivate this keybinding requires manually deleting it from playercfg.lua.
bindup("UI_ShowScreen('thisscreen',ePopup)" , EKEY)
bindup( <code chunk>, <key to bind>)
code chunk - string of lua code encapsulated by [], "", or ''
key to bind - key to bind