No worries. This question came up recently. Tamiya's instructions were off (depending on which version you got!) The steering linkage should be at 90* to the servo saver, which will put the servo saver at a slightly forward angle from the servo.
Here's what you do: Build the linkage to approximately the right length. Attach the servo save to it. Make sure your servo is centered and your wheels are dead straight. Test fit the servo saver on the servo. Is the angle of the rod to servo saver 90*? If yes, clamp 'er down. If no, pop the servo saver off the servo, adjust length and try again. You'll end up with the saver offset forward just a little bit.
I think that's it, but I'm positive I'll be corrected in 3, 2, 1...