Add "Sign Up Question" to post for guests

[Hoodie]

I want to add that popular plugin sing up question, that is usually in the registration page, to the post for guests. Whenever guests post they'll have to answer the question. Right now there's a captcha that guests have to fill in before they post, I want to add;

<!-- SignupQuestions -->{$question}<!-- /SignupQuestions -->

How do I do this to make it so only guests see it. Should I add it to the captcha template? Both will be seen by guests only. What should I do.
~Thanks.