Modifying a PC floppy drive to act as DF0:

[Jope]

Overlapping information in all of these:
http://www.pitsch.de/stuff/amiga/floppy.htm
http://jope.fi/drives/
http://eab.abime.net/showthread.php?t=30944

My opinion even though no-one asked for it: forget cable mods, better install a properly modified mechanism that works with a straight cable. If your drive requires you to swap 2 and 34 around on the cable, then it will not be 100% compatible.

These are very easy to do, and instructions are for most commonly available (second hand) drive mechanisms.