that should be easy, you just have to use input elements on a wml then use the php mail() to send the inputed data. I just put together a quick example of what the form would look like, it should be something like this:
HTML Code:
<p>
<do type="accept" label="Send">
<go href="sendmail.php" method="post">
<postfield name="subject" value="$subject" />
<postfield name="emailaddress" value="$emailaddress"/>
<postfield name="message" value="$message"/>
</go></do></p>
<p>Subject: <input name="subject"/></p>
<p>Emailaddress: <input name="emailaddress"/></p>
<p>Message: <input name="message"/></p>
This is just what the form would look like, you would have to make the sendmail.php script, etc.