You could splice the floppy power supply, which is what I did.
Be carefull! Normally, the amiga power connecter uses yellow as +5V and red as +12V whereas a PC molex connector is usually reversed, yellow is +12V and red is +5V. Grounds are always in the middle. You should look at the pinouts for a molex connector and verify the voltage on the Amiga side with a multimeter before striping soldering and insulating.
Other than this operation, I don't really know of an eaiser way.
