You're very lucky these days ! Arent't you ?
So, be a warrior !
Be sure about plugs orientations !!!!!
Use your Install 3.1 disk to create a short bootable partition (10 mb with standard parameters) and format it.
Then restart and open a shell/CLI
COPY ALL FROM DF0: TO HDD:
Rename your HDD: partition name to Install3.1 (like the disk).
Reboot without any floppy.
You now must have the minimal 3.1 component on your machine working ! if not .... retry and post what happen.
Then, put the IDEFIX floppy, you'll need to install it 2 times !!! The 1st one it will update the IDE device then reboot, and the 2nd it will check for HDD/CD/DVD drives.
This is how I made kick install on my miggys
:-P