DataSource Controls :: ObjectDataSource - Update Method To Pass Entity To The Method In BLL Class?

I have an ObjectDataSource that I want to perform updates using a business entity i.e. Type="Object"). Since the values for the entity are within a user control, I have stored a reference to the control in Session and in the updating event, set the new instance to the value of the entity from the user contol property (which also pulls values from the form viaother properties of the control):

Protected Sub MasterDataSource_Updating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ObjectDataSourceMethodEventArgs) Handles MasterDataSource.Updating
Dim entity As New Login()
Dim accountControl As AccountInfo = TryCast(Session("AccountCtrl"), AccountInfo)
entity = accountControl.Entity
e.InputParameters.Add("entity", entity)
End Sub

And here's the markup for the datasource:

<asp:ObjectDataSource ID="MasterDataSource" runat="server" EnableCaching="true" CacheDuration="10"
SelectMethod="SelectAll" UpdateMethod="Update" TypeName="Data.DAL.LoginDAL">
</asp:ObjectDataSource>

My question is, how can I get the update method to pass this entity to the update method in my BLL class? It seems the Update method requires an ID or reference to the original object to use in determining whether any changes have taken place, but I don't really want to do this. In other words, I just want to use the Update event on my ObjectDataSource to pass my entity to the method ("Update") I set as a property and then let this business method handle the update of the data. Shown below, is the BLL update method I want to call:

Public Overloads Function Update(ByVal entity As Login)
If entity Is Nothing Then
Throw New ArgumentNullException("entity")
End If
MyBase.Update("UpdateLogin", entity.Username, entity.Password, entity.FirstName, entity.LastName, entity.Role, entity.Region, _
entity.Email, entity.Title, entity.TierID, entity.Street, entity.City, entity.State, entity.Zip, entity.Mobile, entity.Phone, entity.Fax)
End Function

When I try to call this as it stands now, I get an error: ObjectDataSource 'MasterDataSource' could not find a non-generic method 'Update' that has parameters: ID, entity. Previously, I'd set up a long list of parameters of basic data types (string, int, boolean), but this is rather cumbersome and I was hoping to use an entity for this (FYI, I also got the same type of error when I tried this approach, but with the ID as the
last parameter in the list). Perhaps what I'm doing here is atypical to how the ODS is normally used?? Has anyone done something like this successfully?