Hey danielvmacedo -
Currently there is no way to take a Texture Sampler and convert to a Texture Object (T2D input). However, the NormalFromHeightMap is a Material Function and you can pull the Instructions out of the Material Function and then use the regular Texture Samplers OR create a copy of the Material function and replace the Function Inputs in the Material Function with the actual Texture Samples you want to use. OR copy the function and pull off the texture samples in the Material Function from the appropriate RGBA channels then when you place the T2d it will pull the separate channels of that Texture as you have set up.
Thank You
Eric Ketchum