you can try this trick!
1st) do this:
<label for="img">
<input type="submit" name="submit" id="img" value="img-btn">
<img src="yourimage.jpg" id="img">
</label>
2nd) style it!
<style type="text/css">
img:hover {
cursor: pointer;
}
input[type=submit] {
display: none;
}
</style>
It is not clean but it will do the job!