If you did this:
Code:
<a href="$post[replylink]" onclick="return mq_click($post[postid])" ...
Then it might actually work, but you wouldn't get any feedback (i.e. text changing). With the image button it works via javascript and cookies, using the javascript functions in clientscript/vbulletin_multi_quote.js. So, you could write your own js functions to toggle the link text, or you could copy the vbulletin_multi_quote.js to another name and change it as necessary.