Assiging a texture in the inspector for use in a Class.

Could someone help me with the following? I would like to be able to use the inspector to set the default settings of my class. In particular a texture used in the class.

class SpawnLabel {

    var labelTexture : Texture2D;
    var labelRect : Rect;
    var labelTitle: String; 

    function spawnLabel (inRect, inTitle) {
        labelRect = inRect;
        labelTitle= inTitle;
    }

    function guiLabel(){
        GUI.Label(labelRect, labelTitle, labelTexture);
    }
}

Is there a way to set the labelTexture without sending it into the constructor every time I want to make an instance of this class?

labelTexture is not available in the inspector, neither can I define a texture outside the class and then go "labelTexture : Texture2D = textureDefinedOutsideClass;" What is the correct way to do this? Thanks in advance :)

var textureDefinedOutsideClass:Texture2D;

class SpawnLabel {

    var labelTexture : Texture2D;
    var labelRect : Rect;
    var labelTitle: String; 

    spawnLabel (inRect, inTitle) {
        labelTexture = textureDefinedOutsideClass;
        labelRect = inRect;
        labelTitle= inTitle;
    }

    guiLabel{
        GUI.Label(labelRect, labelTitle, labelTexture);
    }
}