Setting up a Controller

I have been using MAME for many many years and my I-PAC 2 (emulates the keyboard buttons and mouse) controller works great with this emulator. (Four way and eight -way joystick/Rotary, Spinner and Trackball makes almost every game playable)

I was digging around and looking at the source code for REICAST (The dreamcast emulator). and came across “libretro,h.” first thing i notice was the the various devices that can be use

RETRO_DEVICE_JOYPAD RETRO_DEVICE_MOUSE RETRO_DEVICE_KEYBOARD
RETRO_DEVICE_LIGHTGUN RETRO_DEVICE_ANALOG RETRO_DEVICE_POINTER

I am most interested in the KEYBOARD and MOUSE.
Can I manually edit the retroarch.cfg can and map the ASCII values of the keyboard? if so where do these values go?

Secondly is there a way to enable MOUSE support for games such as the Atari 2600 that uses the paddle control. I was able to accomplish this in the Stella standalone but haven’t figured it out in the core version.

Thanks

Is there a section of the forum that has “sticky posts” for various devices on their setups? If not, it would be a great feature to have to share including downloads for the various configs. The Pinball forums do this and they get revised often.