URL for registration with a specific role

I am running drupal 6.0. It has several different user roles, and I want 2 URL links to allow users to register with a specific role. To clarify what I mean:

• I have the roles Buyer and Seller
• I used the Drupal profile module to add 2 profile fields: "Location" and "Company"
• I installed and configured the Profile Roles module, so the Company field is displayed only to the buyer, and the Location field is displayed only to the seller.

Everything works fine, but I would like to add 2 buttons to my homepage.

• "Buyers register here"
• "Sellers register here"

What I would like if the buyer clicks on his link - I can determine the URL:

• This is the buyer who registers
• When you create this user account, the customer role is automatically assigned, so the correct profile fields are displayed.

Any suggestions on how to do this would be greatly appreciated.