How to add questions to registration page, answers generate member's signature?

[KarateStory]

I want to add questions to the registration page and use the answers to create the member's signature.

I've found lots of info on adding questions to the signup form, such as:
http://www.vbulletin.com/forum/showthread.php?t=108785

How would the answers be inserted into the member's signature?
I only want to insert the answers once at signup, after that the member is free to edit his sig just like everyone else.

dreary details of the mod follow:

*** Start of signup page mod ***

The following optional questions will help us to link to your dojo.
You may edit this information later in your member's control panel.
Your Dojo's Name: ______
Your Dojo's Website URL: ______
Your Style of Karate: ______
Your Belt Rank: "I am a _______ belt."

*** End of signup page mod ***

All inputs are text.

From these questions, you will populate the sig file field of the member's db. His sig file will look like this:

*** start of sig file ***
--
$UserName, $belt_rank Belt, $style
$dojo_name (linked to $dojo_url) (IF $dojo_name is blank AND $dojo_url is NOT blank, print $dojo_url)
*** end of sig file ***

Thanks