Quaternion Rotation and me. I love you.

I wish to rotate an object locally 90 degrees from its original direction, and all future rotation
take this into account when changing direction. I want it to act like the left side of the object is the front. Thanks in advance, I'm not the brightest light bulb. I will make my game though!!

using UnityEngine;
using System.Collections;

public class LookAtTarget : MonoBehaviour
{
private GameObject target;
private Vector3 targetPoint;
private Quaternion targetRotation;...

Quaternion Rotation and me. I love you.