It can be done with a 2-1/4" SP101, but your 3" gun will need to be worn just that much higher up on your calf, and thus may result in either the muzzle protruding beyond your pants cuff into view, or the muzzle rubbing uncomfortably against your ankle bone, or in the gun being so high on your calf that you cannot raise your pants cuff high enough to reliably clear the grip for a draw.
Even with the shorter 2-1/4" gun, it's heavy enough that the sensation of wearing it strapped to your ankle will feel very much like wearing only one old-style all-leather combat boot on that foot. When I used to wear ankle holsters, I found the S&W M642 Airweight Centennial to be significantly less uncomfortable/noticeable than a full-weight all-steel snubby.
