You can do the following:
1) Pack the ADF on the PC using a program like RAR ( use an older version of WinRAR as the miggy version of UNRAR isn't very compatible ).
2) Put the RAR file on a 720k floppy.
3)Create a custom Workbench disk for your miggy, remove all uneccesary commands and programs.
4) Copy *insert your favourite ADF to disk program here* and unRAR to the custom floppy.
5) Boot from the custom floppy.
6) Insert the floppy with the RAR file on, run Cross-DOS, and unpack the RAR-file onto the RAM-disk.
7) Write the ADF stored on your RAM-drive onto a floppy

Re-boot and play your game! :-D