If you intend in using a multi-button joypad or joystick that is compatible with the MorphOS lowlevel.device (which only includes USB and the Pegasos PC-style joystick port as far as I know - I never owned a Mac!), the lowlevel functions are:
JPF_BUTTON_BLUE Blue - Stop JPF_BUTTON_RED Red - Select JPF_BUTTON_YELLOW Yellow - Repeat JPF_BUTTON_GREEN Green - Shuffle JPF_BUTTON_FORWARD Charcoal - Forward JPF_BUTTON_REVERSE Charcoal - Reverse JPF_BUTTON_PLAY Grey - Play/Pause JPF_JOY_UP Up JPF_JOY_DOWN Down JPF_JOY_LEFT Left JPF_JOY_RIGHT Right
Maybe you can map these as keys in the E-UAE config (maybe without the JPF_ part). Maybe you don't even have to and E-UAE will take care of it.
The MorphOS port of E-UAE, if it even supports joysticks at all, must use lowlevel.library - or have Poseidon map USB functions to keys. MorphOS has no other way of controlling joysticks as the original Amiga hardware-banging doesn't work.
Of course i'm writing about using lowlevel library under E-UAE, not DB9 joypad. Poseidon have lowlevel library support in standard, You can configure ANY recognised joypad to use lowlevel.library emulation. E-UAE in standard support joypad, but only 2 button one. My question is how to configure E-UAE to use all buttons from lowlevel.library.
Edit: Where add this strings? in .uaerc or in configstore file?
Edit 2: Lowlevel.library emulation is from MorphOS2.x. I was using joypad over 10 years ago in MorphOS 2.x where few apps and some games support this, now most of apps and games have joypad support.
I've looked at the executable and it does open lowlevel.library, so either it a) opens it isn't really using it (b) is using it only for the standard joy and firebutton (c) has a bug or (d) MorphOS lowlevel.library has a bug.
I don't think it's your settings. Using joy0 and a CD32 kick should automatically enable all the buttons.
I haven't been able to find the source code for the MorphOS build to check what is going on.