no this is what i did.. Start the Pi when emulationstatin starts go to retropie then run retropie-setup.
then do a update retropie setup script.
then setup / configuration and the update APT packages (dont know if this is needed but i did it.
then go back a page and do experimental packages.
then on mine it was the second one “mupen64plus-testing”
it will then download and build the package. do a reboot when it finishes.
when emulation station starts back up go to Nintendo 64 click on a rom and as soon as the screen goes black hit X on the keyboard a window will come up where you can change the default emulator or set a emulator for just that rom. I changed the default to the mupen64plus-testing-rice one.
there is no mupen64plus folder in the beta 2 image. it only uses mupen64plus as far as i can tell so unlike the old one there is no need to install 2 n64 emulators. that’s what worked for me. so that means mupen64plus is already config to use the n64 folder.
after all that i had the edit the configs/n64/mupen64plus.cfg file to add a button the quit the game and add my joy pad button mapping the the autoinput.ini file in that same folder