Set a named float value.

	function Start () {
		// Use the Specular shader on the material
		renderer.material.shader = Shader.Find("Specular");
	}
	function Update () {
		// Animate the Shininess value
		var shininess : float = Mathf.PingPong (Time.time, 1.0);
		renderer.material.SetFloat( "_Shininess", shininess );
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Start() {
        renderer.material.shader = Shader.Find("Specular");
    }
    void Update() {
        float shininess = Mathf.PingPong(Time.time, 1.0F);
        renderer.material.SetFloat("_Shininess", shininess);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Start() as void:
		renderer.material.shader = Shader.Find('Specular')

	def Update() as void:
		shininess as float = Mathf.PingPong(Time.time, 1.0F)
		renderer.material.SetFloat('_Shininess', shininess)