The solution is to surround the anchor in a form, which has the post method and the action you wish to execute. On the anchor put a javascript to submit the form
<form name="submitForm" method="POST" action="/servlet/ServletName">
<input type="hidden" name="param1" value="param1Value">
<A HREF="javascript:document.submitForm.submit()">Click Me</A>
</form>
edit
I think I should mention that this isn't a good idea.
Links take you to pages, that's what users understand them to do. To break the users assumptions and cause a link to POST, to do an irrevocable thing, is generally considered a bad idea.
Use a button, label it semantically, then your user knows that clicking this does something.
second edit
I really need to emphasise that this isn't a good idea at all.
This breaks the internet.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…