No a highlight map is actually an image map that shows where highlights go.  The highlight being black changes things a bit. Try this...on a simple shader if necessary. Set highlight to around 14% and shininess to 2%. Highlight percentage gets stronger the higher the number. Shininess controls the size of that highlight area. Higher tightens the noose and makes it smaller...like plastic. But if you have to much highlight you will blow it out any way. Look at this simple shader. I grabbed it from the stuff and changed those 2 settings. Not great shader, but was dark to show what I mean more clearly.

No need to think outside the box....
    Just make it invisible.