When I was a child, in the early/mid 90s, I once saw a really scary movie at a friend's place. I only remember a scene where an alien spaceship is on its way to Earth to invade it. Two aliens are onboard the spaceship (there may have been others besides those two) and they go into a room where they undergo a procedure to turn into humans. First a layer of muscle is formed, followed by veins and last a layer of skin. I remember the scene of the transformation being very graphic, like a b-movie, and there wasn't very much light. That's all I remember, and it's driving me crazy not knowing the name of this movie - I have asked a lot of people about it, but without any results. I hope you guys can help me. Thanks in advance! :)