In your scenario, the most appropriate way to adapt your existing logic in your custom login controls is to implement membership providers that will match yours. In that way, it would lessen the work needed to hook login scenarios using the Login controls found in VS 2005.

There are certain threads here in the forums that would give you a good headstart:

http://forums.asp.net/t/1330875.aspx

http://forums.asp.net/t/1303349.aspx

http://forums.asp.net/t/1324539.aspx

Personally, since you already have logic in place in your custom login controls, you can extend the SqlMembership class to handle that one and define it as a provider in your web.config. Suppose you have enclosed your own logic in a membership provider defined as "myCustomProvider" in the web.config file, you can extend the button click of the login control to do something like:

Membership.Providers["myCustomProvider"].ValidateUser(Login1.UserName, Login1.Password)

HTH

Broodmdh:

but I don't know how to get the login control to use them,

By default , the login control and other controls  use Membership provider , but you let the login control work with  your custom database table ,

Please take a look at this thread :

 http://forums.asp.net/t/1276534.aspx