In your ActionScript package, add the Comments preference. In the editor part add:
{ shellVariables = (
{ name = 'TM_COMMENT_START';
value = '// ';
},
{ name = 'TM_COMMENT_DISABLE_INDENT';
value = 'YES';
},
{ name = 'TM_COMMENT_START_2';
value = '/* ';
},
{ name = 'TM_COMMENT_END_2';
value = '*/';
},
);
}
and finally, at the bottom, set the area selector: scope.actionscript.2
Here is an image of what mine looks like 
Reload Bundles .