i put the ase models in openarena/baseoa, loaded them into radiant, used them in the map and saved the map file. i've opened the map file in a text editor and the relevant line reads...
"model" "left.ase"
...since the ase models in the pk3s are in models/mapobjects should i edit the .map file so that the line reads...
"model" "models/mapobjects/left.ase"
...and reload it into radiant?
"everything in it's right place"
In a very simple way, Pk3 files contain all files and directories supposed to be in your base directory (baseoa), after all, that's where those Pk3 files are. The models should be stored in "models/mapmodels/" inside that "baseoa" folder. So create a "models" folder in "baseoa" and a "mapmodels" directory in "models". Very often, models are stored into another folder inside "mapmodels" (so it is also possible to add skins or model's variations there).
When you load GTKRadiant and put a "misc_model" entity in your map, you can choose the model path with the "model" button (or adding the "model" key and the "path" value). The model button will browse your baseoa/models/mapmodels directory automatically (on your drive, Radiant won't let you explore what's in Pk3 ressources files). You'll just have to select your file from there.
There shouldn't be any need to change anything with txt editors.