如何在自定义MembershipProvider上调用Initialize？

using System.Configuration;
using System.Web.Security;

public class CustomMembershipProvider : MembershipProvider
{
    public override void Initialize(string name, System.Collections.Specialized.NameValueCollection config)
    {
        // 初始化配置信息
        base.Initialize(name, config);
    }

    // 其他 MembershipProvider 的方法实现
}

  <membership defaultProvider="CustomMembershipProvider">
    <providers>
     <clear />
      <add name="CustomMembershipProvider" type="CustomMembershipProvider" />
    </providers>
  </membership>
</system.web>