In vice: load the daffy-duck-ds1.d64 to device 8 (file->attach disk image->unit #8). Then run:

    LOAD "DAFFYDUCK",8
    RUN

Edit: for debug controls you rename the "OFF" file to "ON":

    OPEN 1,8,15,"R:ON=OFF":CLOSE 1

Verify that you did it right with:

    LOAD "$",8
    LIST

You should see an entry that says "ON" at the bottom of the list. Then you can run the game as above and will be given an option to have infinite energy and to skip the level with space bar. It also has a nice little banner at the beginning that you don't get with it off.