Yes, there are JavaScript PNG fix libraries that allow CSS background positioning in IE6. One such library is IE PNG Fix, which is a small JavaScript utility that fixes PNG transparency issues in IE6 and also enables the use of alpha-transparent PNGs as CSS background images with background positioning.

Here’s how you can use IE PNG Fix to enable background positioning for alpha-transparent PNGs in IE6:

1. Download the IE PNG Fix library from its website (https://github.com/DD_belatedPNG/dd_belatedpng) and save it to your project directory.

2. Include the IE PNG Fix script in the head section of your HTML document, before any other scripts that reference alpha-transparent PNGs:

<!--[if lte IE 6]>
<script src="iepngfix.js" type="text/javascript"></script>
<![endif]-->

3. Add the following CSS rule to your stylesheet to apply the alpha-transparent PNG as a background image and specify the background position:

.my-element {
  background: transparent url(my-image.png) no-repeat 0 0;
  *background: url(blank.gif); /* IE6 hack to trigger hasLayout */
  _background-position: 0 0; /* IE6 hack to specify background position */
}

In this example, the first line sets the alpha-transparent PNG as the background image of .my-element and specifies the background position as 0 0. The second and third lines are IE6-specific hacks that are required to trigger the PNG fix and apply the correct background position.

Note that the IE PNG Fix library may not work in some edge cases or may cause performance issues on large pages, so it’s important to test thoroughly and consider alternative solutions where necessary.