I've not tested this extensively, and not yet cross-platform, but for both Midori and FF3.x (on Ubuntu 8.04) the button tags take styles for :hover,:focus and :active (similar to a tags).
This works, certainly:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html>
<head>
<title></title>
<style type="text/css">
button {color: #f00;
background-color: #ccc;
border: 0 none transparent;}
button:hover {color: #0f0; }
button:active {color: #00f; }
</style>
</head>
<body>
<div id="wrapper">
<form method="post" action="" enctype="form/multipart">
<fieldset>
<label for="input1">Label 1:</label>
<input id="input1" name="input1" type="text" />
<label for="input2">Label 2:</label>
<input id="input2" name="input2" type="text" />
</fieldset>
<fieldset>
<button class="reset" type="reset">Reset</button>
<button class="submit" type="submit">Submit</button>
</fieldset>
</for>
</div>
</body
</html>
Demonstration at: http://www.davidrhysthomas.co.uk/so/buttons.html
Further edited to respond to question-edit:
You could try adding a third list element, and naming them (I'd further recommend using fieldsets rather than lists, but let's go with what you've got).
<head>
<link rel="stylesheet" type="text/css" href="regularStylesheet.css" />
<!--[if ie lte7]>
<link rel="stylesheet" type="text/css" href="ie-adaptations.css" />
<![endif]-->
<form name="contact" action="index.php" method="post">
<ul>
<li>
<label for="name" class="name">Name</label>
<input type="text" name="name" id="name" size="30" />
</li>
<li class="submit-buttons">
<button type="submit" class="submit">Send</button>
<input type="hidden" name="submit" value="yes">
</li>
<li class="submit-links">
<a href="where/ever/you/send.html">Send</a>
<input type="hidden" name="submit" value="yes">
</li>
</ul>
</form>
Then in the regular CSS add:
li.submit-buttons
{
display: block;
}
li.submit-links
{
display: none;
}
And reverse that in the IE-adaptations.css:
li.submit-buttons
{
display: none;
}
li.submit-links
{
display: block;
}
It's not perfect by any means, but it doesn't upset devices using forms-mode and should allow the buttons to show; and should only force IE 7 (and below) to display the links. So...hopefully shouldn't upset accessibility too much.