Control two stepper motors with joystick

My idea is to stack two Stepper Bricks and attach a Joystick Bricklet to one of the Stepper Bricks.

Since the API is thread safe, I can have a thread monitoring the state of the joystick and can change the state of the step motors accordingly.

Now, is it possible to change the speed of the stepper motor as it moves. That is, can I do the following,

stepper_set_max_velocity(my_stepper, 10);
stepper_drive_forward(my_stepper);
// at a later time, while still moving, will this call increase the 
// stepper motor velocity?
stepper_set_max_velocity(my_stepper, 100);