Set current context class loader

I have 2 ClassLoaders, one which I don't have access to source code and second which I'm loading classes now. ( I'm using java agents to inject code. )

My problem is when I try to load class which has been loaded by the different ClassLoader, it's not working.

// some different class loader
// also this is the ClassLoader which loaded GL11
ClassLoader cl = getDifferentClassLoader();

this.getClass().getClassLoader() == cl // false

GL11.glPushMatrix(); // NoClassDefFoundError

But when I call it using reflection, it works

Class<?> clazz = cl.loadClass("org.lwjgl.opengl.GL11");
clazz.getDeclaredMethod("glPushMatrix").invoke(null); // this works

I tried something like this but it's not working :(

Thread.currentThread().setContextClassLoader(cl);
GL11.glPushMatrix();

Is something like this possible?