How can I add cursor acceleration?

I'm looking to build a custom cursor that changes appearance and travels through walls etc, but am stuck at achieving proper acceleration. Multiplying the mouse input vector by itself wields it very erratic, even if I only use 20%.

 public float spd = 0.5F;
 public float acc = 0.2F;
 float h = Input.GetAxis ("Mouse X");
 float v = Input.GetAxis ("Mouse Y");
 if (h!=0){
 if (v!=0){
 transform.Translate (new Vector3 (h*acc, v*acc) * spd);}
 }}

Also tried adding rigidbody force, but no change at all:

 Rigidbody rig;
 void FixedUpdate () {
 Vector3 mouseDelta = new Vector3( Input.GetAxis("Mouse X") , Input.GetAxis("Mouse Y"), 0f ) * s;
 rig.AddForce(mouseDelta * rig.mass * Time.deltaTime);
 }

If anyone can provide tips, it's been bugging me all day, thanks.