I think what you might be seeing the option to bake in Max is a specular lighting map. That's not the same thing - you'd be baking what the specular lighting looks like on the model for the current camera/light position and that's not what you're after. What you're wanting to make is a texture map that defines how bright…
I'm guessing that you are at a place where you are trying to fill in gaps to your understanding since you said you have seen tutorials but they "tend to be missing certain things". Simply put, most spec maps are made by taking the diffuse map in Photoshop and quickly editing it. Below is one of my own where I simply took…