I have always tanned easy, had never tried melanotan before, and was skeptical about whether melanotan would work. I was surprised how well it worked and how quickly. Hadn't had hardly any sun where I live until recently, but I spent some time in the sun working on getting at least a bit of a tan and then spent a few days in Las Vegas in the sun. I tried the melanotan when I got back figuring I might use it maintain what I had or I might get a little bit darker. After about a week, I quit using it because I got so many comments on my tan and how dark I had become so quickly. I had to keep explaining that it was because I had been in Las Vegas and then spent a weekend working outside all day. I was surprised at how effective the stuff really is.
As to the question about taking it IM, I have no idea, just saw a thread on melanotan and it's one thing that does a remarkable job of doing exactly what they say it will.