For reference in the Google Group

gistfile1.cs

//our base implementation
[SitecoreType]
    public class GlassBase : IGlassBase
    {
        [SitecoreId]
        public virtual Guid Id { get; private set; }

        [SitecoreInfo(SitecoreInfoType.Language)]
        public virtual Language Language { get; private set; }

        [SitecoreInfo(SitecoreInfoType.Version)]
        public virtual int Version { get; private set; }

        [SitecoreInfo(SitecoreInfoType.Path)]
        public virtual string Path { get; private set; }

        [SitecoreInfo(SitecoreInfoType.Name)]
        public virtual string Name { get; set; }

        [SitecoreInfo(SitecoreInfoType.Url)]
        public virtual string Url { get; private set; }

        [SitecoreInfo(SitecoreInfoType.TemplateId)]
        public virtual Guid TemplateId { get; private set; }

        [SitecoreInfo(SitecoreInfoType.TemplateName)]
        public virtual string TemplateName { get; private set; }

        [SitecoreChildren(IsLazy = false)]
        public virtual IEnumerable<GlassBase> BaseChildren { get; set; }

        [SitecoreField]
        public virtual DateTime Publish { get; set; }

        [SitecoreField]
        public virtual DateTime Unpublish { get; set; }

        //[SitecoreField("__Sortorder")]
        //public virtual string Sortorder { get; set; }

        public IEnumerable<T> GetChildren<T>(string templateName) where T : GlassBase
        {
            var items = new List<T>();
            ISitecoreContext context = new SitecoreContext();
            if (BaseChildren != null)
                items.AddRange(
                    from item in BaseChildren
                    where item.TemplateName.ToLower() == templateName.ToLower()
                    select context.GetItem<T>(item.Id));
            return items;
        }

        public IEnumerable<T> GetChildren<T>(Guid templateId) where T : GlassBase
        {
            var items = new List<T>();
            ISitecoreContext context = new SitecoreContext();
            if (BaseChildren != null)
                items.AddRange(
                    from item in BaseChildren
                    where item.TemplateId == templateId
                    select context.GetItem<T>(item.Id));
            return items;
        }
    }



//the parent class that sitecore is actually creating
[SitecoreType(TemplateId = "<myGuid>")]
    public class ContentItem : GlassBase
    {
        [SitecoreField]
        public virtual string IContentItemTitle { get; set; }
        [SitecoreField]
        public virtual string IContentItemOriginalId { get; set; }
        [SitecoreField]
        public virtual string IContentItemType { get; set; }
        [SitecoreField]
        public virtual string IContentItemSecurityGroup { get; set; }
        [SitecoreField]
        public virtual string IContentItemContributor { get; set; }
        [SitecoreField]
        public virtual string IContentItemAuthor { get; set; }
        [SitecoreField]
        public virtual DateTime IContentItemPublicationDate { get; set; }
        [SitecoreField]
        public virtual string IContentItemSource { get; set; }
        [SitecoreField]
        public virtual string IContentItemCategory { get; set; }
        [SitecoreField]
        public virtual string IContentItemSetting { get; set; }
        [SitecoreField]
        public virtual string IContentItemSpecialtyArea { get; set; }
        [SitecoreField]
        public virtual string IContentItemComments { get; set; }
        [SitecoreField]
        public virtual bool IContentItemPrioritizeContent { get; set; }
        [SitecoreField(Setting = SitecoreFieldSettings.RichTextRaw)]
        public virtual string IContentItemAbstract { get; set; }
        [SitecoreField]
        public virtual DateTime IContentItemReleaseDate { get; set; }
        [SitecoreField]
        public virtual string IContentItemDateDisplayFormat { get; set; }
        [SitecoreField]
        public virtual bool IContentItemDisplayInResults { get; set; }
        [SitecoreField]
        public virtual IEnumerable<ContentItem> IContentItemRelatedTerms { get; set; }
        [SitecoreField]
        public virtual IEnumerable<ContentItem> IContentItemSeeAlso { get; set; }
        [SitecoreField]
        public virtual string IContentItemDomain { get; set; }
        [SitecoreField]
        public virtual string IContentItemLevel { get; set; }
        #region TemporaryCategoryStorage
        [SitecoreField]
        public virtual string Cat1 { get; set; }
        [SitecoreField]
        public virtual string Cat2 { get; set; }
        [SitecoreField]
        public virtual string Cat3 { get; set; }
        [SitecoreField]
        public virtual string Cat4 { get; set; }
        #endregion
        public string FormattedDate(DateTime date)
        {
            return date.ToString(IContentItemDateDisplayFormat);
        }
    }


//The concrete class
[SitecoreClass(TemplateId = "myGuid")]
    public class HtmlItem : ContentItem
    {
        [SitecoreField(Setting = SitecoreFieldSettings.RichTextRaw)]
        public virtual string HtmlItemContent { get; set; }
    }
    
    

Can you add the code that uses these classes to create the items in Sitecore?