styles = new TextField.StyleSheet();
styles.setStyle(".green", {fontSize: '24px', color: '#00CC00'} );
//styles.setStyle(".almostblack", {color: '#010000'} );
this.createTextField("theField_txt", 1, 10, 10, 300, 300);
theField_txt.multiline=true; theField_txt.html = true;
theField_txt.styleSheet = this.styles;
var theHTML='<ul><li>stuff</li><li>some green text: <span class="almostblack"> </span><span class="green">Green!</span></li><li>more stuff</li></ul>'
theField_txt.htmlText = theHTML
will show up like this:

If you uncomment the almostblack style then the green bullet will look black.

If you make the almostblack style color really black 000000 instead of almost black, then the bullet will be green.
I'm assuming this will get fixed at some point and when that happens the almostblack hack won't really do anything other than be extra code that needs to be removed.
If/when it gets fixed then any pretty colored bullets made by doing this
var theHTML='<ul><li>stuff</li><li> <span class="green"> </span>black text with a green bullet</li><li>more stuff</li></ul>'
will suddenly be black.
there's also this
var theHTML='<ul><li>stuff</li><li><span class="green"> </span>black text with a black bullet</li><li>more stuff</li></ul>'
which makes a jumbo sized black bullet.