body {       cursor: url('path-to-image.png'), auto; }

The "auto" is a fall-back so that if the custom cursor link is broken or it can't be loaded the default cursor will show instead, so your page doesn't completely break.

This may or may not work on HEE, because I've discovered some of the styling is hard-coded into the HTML as inline styles, which have the highest specificity and override everything, but feel free to try it. I'm sure the style tags are a leftover from before CSS was more than just a way to style a few select elements (I'm old enough to have written pages styled with HTML tables and inline font styles/colors before CSS existed at all).

You might need to resort to !important because of the specificity issue.

Good luck.