Access the x or y component using [0] or [1] respectively.

	var p : Vector2;
	p[1] = 5; // the same as p.y = 5

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    public Vector2 p;
    void Example() {
        p[1] = 5;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	public p as Vector2

	def Example() as void:
		p[1] = 5