Everything expect texture:

                anotherplayer =  GameObject.CreatePrimitive(PrimitiveType.Plane);
                anotherplayer.name = updatexml.players[i].username;
                anotherplayer.transform.localScale = new Vector3(0.0903f, 0.0903f, 0.0903f);
                anotherplayer.transform.eulerAngles = new Vector3(62.68924f, 184.4452f, 4.010004f);
                anotherplayer.transform.position = new Vector3(updatexml.players[i].x_coordinate, updatexml.players[i].y_coordinate, updatexml.players[i].z_coordinate);

For assigning a texture to the object, I believe you can use the following (Javascript) placed on the object in question:

var myTexture: Texture2D; 

function Start(){ 

    renderer.material.mainTexture = myTexture;
}

A similar forum post and the Unity Scripting Reference.

I don't know C# unfortunately but this post would seem to suggest you can use a similar line like the following:

public Texture mytexture; 

void Start() 
{ 
   renderer.material.mainTexture = mytexture; 
}

Hope that helps.