A right angle Phillips/Flathead screwdriver would be the best to use not to scuff up the body or pickguard, or you can do what Jim suggested and just lay something between the body and driver...(a piece of Leather works very nicely, which I would also use if using a Right angle driver just in case you slip!).
Yes...We can retrofit our older basses with the spoke wheel, however the Channel would still be there (unless you ordered a New Pickguard for the Vintage models), and the wheel route itself it slightly wider.
What about replacing the "slot" nut w/ a "hex" nut (if one is available for the Sad. rod). Then you could buy a Fender wrench which would work well w/ the older style Sad. pg slot, providing the i/s hex is the same size(3/16" I believe). That wrench has a nice log shaft & a "T" handle & has a ball-hex end so you can adjust the angle of use.http://www.fender.com/products/search.php?partno=0048693000#