you can export model from gmax in format that can import Lithunwrap and here get bmp from Uwmap , you should search in main gmax forum about this method, or you can unwrap model in gmax and take screenshot from Unwrap window

here is 1 tutorial about this http://www.studio-erebus.com/studio/tutorials/2003/uvw/uvw-dice.html

or here using lithUnwrap + 3ds max , you must register to get access http://www.map-craft.com/modules.php?name=video_tuts&file=uv101

get bmp from uwmap in LithUnwrap is easy, simply unwrap object in gmax , make all faces near one another. i made test, export md3 from gmax with uwmap and Unwrap , import in lithunwrap and it works