As you might know, the Commodore peripherals are "intelligent", which means they include a CPU of their own (typically a 6502) and controller software. You can send a job to the drive and continue working with the main computer if no output from the drive is expected.
Now, a typical PC floppy is a "dumb" animal, which needs a controller device just like the ones integrated on your PC motherboard or in the old days was delivered on an ISA expansion card (together with serial ports etc). Of course, you could try to drive a PC floppy controller from the C64 (or emulate the floppy controller in software), but I'm not sure how easy and efficient it would be.
I'm not quite sure what you would like to accomplish, but maybe you want to buy something like the FD-2000 which is a high-density 3.5" drive for the Commodore computers which can read IBM PC disks. I believe there are DIY projects on the web where you could put together your own drive by using a PC floppy, a controller device and some glue logic. Maybe this is exactly what you are looking for? Technically you are building your own interface between the floppy and the computer.
By the way, there are a couple of projects similar to Serial Slave, e.g. IDE64, HDD64 and so on. The only difficulity is to know where to look...