Bookmark to insert strikethrough tag

I have a bookmark set up in IE8 that allows me to easily insert text into a ticketing system I use for work. The code below correctly inserts an <s> tag at the cursor but I need to modify it to insert the closing tag </s> at the end of the selection:

javascript:var%20message%20=%20'<s>';var%20comment%20=%20document.getElementById(%22description%22); var%20startPos%20=%20comment.selectionStart;var%20endPos%20=%20comment.selectionEnd;var%20cursorPos% 20=%20endPos;var%20scrollTop%20=%20comment.scrollTop;comment.value%20=%20comment.value.substring(0,% 20startPos)%20+%20message%20+%20comment.value.substring(endPos,%20comment.value.length);cursorPos%20 +=%20message.length;comment.focus();comment.selectionStart%20=%20cursorPoscomment.selectionEnd%20=%2 0cursorPoscomment.scrollTop%20=%20scrollTop;

Any help is much appreciated!