Not in 0.73... I've configured it to save it to ~/apps/mapper.txt, which is user writable. (Unless you override it in the config file!)

I think this is more a scancode-or-keysym issue. There's an option in DOSBox Prefs.txt called "usescancodes": try switching that on and off and remapping.
Nokia.sys will do nothing here, it's just for N810 FN-keys.

I will provide a debug-enabled build of DOSBox later this week (I hope).

The d-pad keys work with the default configuration for me (at least in QBASIC). And I can assure you I have no /usr/share/dosbox/ directory (WHAT do you have there?).