Your sort of stuck in chicken and egg situation. What to do is construct a custom boot floppy, which includes idefix. You can boot the A1200 using it and then run HDToolBox to configure the HDD. When configuring the HDD create a small no more than 4GB boot partition and isntall workbench on it. For my set up I have my 80GB drive configured with a 2GB boot partition (DH0) and a 2GB cache partition (DH1) and the rest is (DH3).
Weed