This is a complete shot in the dark, but try:
<body onLoad="self.focus();document.foo.bar.focus()">
if the HTML was something like:
<form name="foo">
<input type="submit" name="bar" value="submit">
Haven't tried it...but I know it works if you want to place focus on a field when a page loads. I speculate if the focus is on the submit button, when they press enter...it will submit.
Best of luck,
Christian