I would suggest a couple of things: on Gen I and non-ABS Gen II rear calipers, needle nose pliers are a fair alternative to the small, simple spanner tool shown in the Service Manual...but be careful not to slip and tear dust boots. In my opinion, this is not such a great alternative on Gen II ABS rears as the caliper must be dismounted, hand held, and the two notches are not all that easy to engage. The "special tool" for the ABS Gen II rear caliper is more complex, takes a little dexterity...but does work well without risk of bodily harm.
If one is committed to a "workaround" and attempts the needle nose plier route, try not to make a hole in your hand...as it does require applying some force to an unstable platform.