Is required that you have a form?
If not, then you could use this:
<div>
<input type="hidden" value="ServletParameter" />
<input type="button" id="callJavaScriptServlet" onclick="callJavaScriptServlet()" />
</div>
with the following JavaScript:
function callJavaScriptServlet() {
this.form.action = "MyServlet";
this.form.submit();
}