I finally figured out why I was having trouble using non-box style cell packs like those in Telejano and maybe Tenebrae.
The models are not .mdl, they are those .bsp files like b_rock0.bsp (I was aware of this, but wasn't thinking about it at the time).
So ... I decided to copy those into joequake/maps
I start JoeQuake and get ...
mod_loadbrushmodel: maps/b_rock0.bsp has wrong version number (860898377 should be 29).
So what do I need to do to be able to use them?
Here is the b_rock0.bsp for anyone who needs it to experiment:
b_rock0.bsp (goes in joequake/maps folder)