Save Some Info In The Session Within A Custom MembershipProvider?

I want to save some info in the Session when the users successfully logins with my custom MembershipProvider, but I have no access to the Session in the provider's ValidateUser method.

public class CustomMembershipProvider : MembershipProvider
{
/* Override other methods and properties here */
public override bool ValidateUser(string username, string password)
{
/* do something to validate the username and password
* and set the validUser variable */
if (validUser)
{
/* want to store some info in the Session here, but I can't access
* it here, because this is not a Page */
}
return validUser;
}
}