It can easily be done if you know some basic html and a little css.
Your up-sell info would go inside the area I labelled "YOUR HTML GOES HERE". Your custom html needs to be on a single line (no line breaks) and wrapped with quotes.
function EJEJC_lc(th) { return false; }
function EJEJC_config() {
EJEJC_BGCOLOR = "#000";
EJEJC_OPACITY = 60;
EJEJC_POSTCALL=true;
}
function EJEJC_shown() {
jQuery("#imgHeader").attr("src", "/images/MyNewHeader.png");
ejejc_jQuery("#tdSell").attr("innerHTML","YOUR HTML GOES HERE");
}
Sample:
ejejc_jQuery("#tdSell").attr("innerHTML","<p>What others have also purchased</p>");
Check out post: http://www.e-junkie.com/bb/topic/6645
See a working example at www.jumpstartbikes.com
Hopefully that helps.