Sure. In essence, a "Lerp" is nothing more than:

return from + (to-from) * t;

In Unity, the Lerp functions also clamp 't', ensuring the range doesn't go below zero, or above one. So to implement a "Lerp" function for Vector2's yourself, it can just be a 2-line function:

public static Vector2 Lerp(Vector2 from, Vector2 to, float t)
{
    t = Mathf.Clamp01(t);
    return new Vector2(from.x + ((to.x - from.x) * t), from.y + ((to.y - from.y) * t));
}

Although it does seem like a bit of an oversight that it wasn't included in the Vector2 class.

For the record, Vector2.Lerp does exist in Unity 3.