I believe you can just run:
1> setautoboot dh0:
from your DataFlyer disk, and "re-bless" your hard drive so that the Amiga can detect it properly.
You may need to only use a standard filesystem, like the Amiga FFS. I never ran 3.1 on an A500, but I remember having to do this on my 1.3/2.1 dual-boot A500 with DataFlyer.
