Pepedog,
Yes, you'd have to sign up with a new account for each of your eBay ID's. I would suggest using KickItBack with your ID that you normally buy with. You could then create a toolbar link in your browser for eBay that uses your KickItBack referral link, so that every time you buy on eBay you will get credit.
For more information on how to do this:
http://www.kickitback.com/Tools/ToolBarLink.aspx
-Kevin