Hi John,
i found out two ways to accomplish what you want, the first thing works only for a submit button (but is really easy) and the second one involves a bit more js but works for any form-button...
the first one (out of the php-manual - variables from outside PHP)
<input type=image src="image.gif" name="sub">
where Image.gif is the image for the button...
the second one, basicly uses the Form.submit() function... with the onClick Event (both JS) ... just try and if you have any problems ask...
cya Rob