// Modifies only the vertical slider thumb style of the current GUISkin
    var vSliderValue : float = 0.0;
    var style : GUIStyle;
    function OnGUI () {
        GUI.skin.verticalSliderThumb = style;
        vSliderValue = GUILayout.VerticalSlider (vSliderValue, 10.0, 0.0);
    }

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public float vSliderValue = 0.0F;
    public GUIStyle style;
    void OnGUI() {
        GUI.skin.verticalSliderThumb = style;
        vSliderValue = GUILayout.VerticalSlider(vSliderValue, 10.0F, 0.0F);
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public vSliderValue as single = 0.0F

    public style as GUIStyle

    def OnGUI():
        GUI.skin.verticalSliderThumb = style
        vSliderValue = GUILayout.VerticalSlider(vSliderValue, 10.0F, 0.0F)