Alright, well I've made some progress, but not in the direction I had hoped.
Unfortunately, I've hit a big limitation. functions can only call functions inside of the same Lua file as well as specific global functions. I haven't been able to figure out why mission Lua scripts can seem to call some of these functions without a problem, such as notoriety_set on line 208 of bh01.lua. However, trying to call these functions while hooked into pause_menu.lua and hud.lua has no effect. I'm still experimenting here but something tells me we may end up needing a scripthook after all.