You would probably damage a normal floppy drive attempting to do this. Many (most?) PC drives activate a "head load" mechanism which slightly squeezes the heads closer to the disk from a neutral position *after* the drive has achieved "READY" status, IE, hit the target RPM; on such a drive rapidly diddling the motor-on signal could A: damage that mechanism, and B: the heads wouldn't be in a position to read or write anyway, so you'd be wasting your time.
(8" floppy drives and early "Shugart Standard" interface 5 1/4 drives had a separate "Head Load" signal that the controller could use to engage head loading independent of the motor on signal; this was useful to save disk wear on 8" floppy drives powered by AC motors that ran continuously as long as a disk was inserted. PC interface drives are set up to do it automatically.)
Yes, that being my point. It's not "plug and play". If you're willing to cut some traces or otherwise pirate control of the spindle motor it's "easy" enough to spin it at some other speed. Ancient floppy drives usually just controlled their drive speed with a variable resistor but modern ones generally use a PWM/tachometer feedback system. If you were to try modifying a PC drive to act like a Mac drive it would by necessity be more complicated because:
A: You need to support multiple speeds, not just one that's an even 1/2 division of the normal speed, and:
B: You will have to force the drive to spin quite a lot faster than normal rather than slower. Determining whether a given mechanism only designed for 300 RPM (or 360RPM in some cases, as there's a Japanese 3 1/2 floppy drive standard that spins at that and quite a few drives "secretly" support as well) will handle 590RPM without blowing up might take some empirical testing.