function saveRecord(id:number, record:tblEvents) {
    ExtFK.Events.SaveRecord(id, record,  function (ret: tblEvents) {
        alert("saved " + ret.EventID);
    }
}

<ExtModel("tblEvents", "EventID")>
<ExtForm(FormType.ftComplex)>
Public Class Events
    Inherits _AJAXHandler

    Public Overrides Function EditRecord(ID As Integer) As Object
        Return MyBase.EditRecord(ID)
    End Function

    Public Overrides Sub DelRecord(ID As Integer)
        MyBase.DelRecord(ID)
    End Sub

    Public Function SaveRecord(ByVal ID As Integer, ByVal oEvent As tblEvents) As IEnumerable
        Dim uEvent As tblEvents = db.tblEvents.FirstOrDefault(Function(v) v.EventID = ID)
        If uEvent Is Nothing Then
            If ID > 0 Then Throw New Exception(String.Format("Запись семинара id {0} не найдена в базе", ID))
            uEvent = New tblEvents
            db.Entry(uEvent).State = EntityState.Added
        End If
        uEvent.Name = oEvent.Name
        uEvent.Description = oEvent.Description
        uEvent.Price = oEvent.Price
        uEvent.Length = oEvent.Length
        uEvent.Description = oEvent.Description
        uEvent.CategoryID = oEvent.CategoryID
        db.SaveChanges()
        Return (From v In db.cvEventsList.AsNoTracking Select v.EventID, v.Price, v.DateStr, v.Name, v.Date Where EventID = uEvent.EventID).ToList()
    End Function

    Public Overrides Function GetList(Page As Integer, RecordCount As Integer, Optional Filter As String = "", Optional Order As String = "") As PagingResponse
        Dim pr As PagingResponse = MyBase.GetTypedList(Of cvEventsList)(Page, RecordCount, Filter, Order)
        pr.Records = (From v As cvEventsList In pr.Records Select v.EventID, v.CategoryID, v.Category, v.DateStr, v.Name, v.Price).ToList
        Return pr
    End Function
End Class

form.action = ExtFK.Events.SaveRecordUrl();
form.submit()

Inherits _NMLHandler
'и всё. остальной код не меняется.

//эта часть генерируется полностью 
Ext.define(ExtFK.Category.Model, {
    extend: 'Ext.data.Model',
    idProperty: 'CategoryID',
    fields: ['CategoryID', 'Name']
});

//эта частично
Ext.define(ExtFK.Category.Form, {
    extend: 'IForm',
    items: [
        {
            fieldLabel: 'ID',
            name: 'CategoryID',
            disabled: true
        },
        {
            fieldLabel: 'Название',
            name: 'Name',
            width: 800
        }
    ]
});

            <div class="editor-label">
                @Html.CheckBoxFor(Function(m) m.RememberMe)
                @Html.LabelFor(Function(m) m.RememberMe)
            </div>