About Texture2D and ResourceCache in Lua API

I writing small game using Lua. I have 2 questions:

  1. How to manually add resource to cache?
  2. How to get image from Texture2D (to get/set some pixels for example)?
    In AngelScript API I found methods Texture2D.GetImage() and ResourceCache.AddManualResource (Resource@), but there is not alternatives for Lua Script API?