Make sure you set the steering angle to 0 on your rear wheel blueprint, otherwise all 4 wheels will turn when you give steering input, unless you want that.
I am not quite sure what you are looking for, if you want the wheels to be able to turn so the vehicle moves sideways, you could try increasing the steering angle to 90 for both the the front and the rear wheels, so they go sideways when you steer fully to the left or right and push the throttle. Is that what you mean?
EDIT: If that is the case, multiply your regular steering axis values (A & D) by 0.75 before connecting to Set Steering Input, this will prevent the wheels from turning 90 degrees while steering. Then for your Q and E just use the full axis value to set the steering input.
That make sense? I can upload an image of what I mean.