Thanks.
Oblivion Knight, This is the only way I know of.. You might try placing the button in a different place. Maybe under the user's location on the left.
corsacrazy, Try this (haven't tested it myself).. And if that doesn't work try searching for "javascript toggle function" on google. It can be done but I didn't bother adding it because its hard to find one that works with all browsers.
Code:
<input type="checkbox" id="p$post[postid]" onclick="if(document.p$post[postid].p$post[postid].checked)
document.post.message.value = document.post.message.value + document.p$post[postid].elements[0].value;
else document.post.message.value = document.post.message.value -
document.p$post[postid].elements[0].value">