Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
　　If IsPostBack Then
　　　　Return
　　End If

　　FpSpread1.ActiveSheetView.Cells(0, 0).CellType = New CustomCell()
End Sub

<Serializable()>
Public Class CustomCell
　　Inherits FarPoint.Web.Spread.TextCellType

　　Public Overrides Function GetEditorControl(ByVal id As String, ByVal parent As System.Web.UI.WebControls.TableCell, ByVal style As FarPoint.Web.Spread.Appearance, ByVal margin As FarPoint.Web.Spread.Inset, ByVal value As Object, ByVal upperLevel As Boolean) As System.Web.UI.Control
　　　　' 既定の処理をコメントアウト
　　　　'Return MyBase.GetEditorControl(id, parent, style, margin, value, upperLevel)

　　　　' ReadOnlyに設定したTextBoxを編集時に使用
　　　　Dim tb As TextBox = CType(MyBase.GetEditorControl(id, parent, style, margin, value, upperLevel), TextBox)
　　　　tb.Attributes("readonly") = "readonly"
　　　　Return tb
　　End Function
End Class

protected void Page_Load(object sender, EventArgs e)
{
　　if (Page.IsPostBack) return;

　　FpSpread1.ActiveSheetView.Cells[0, 0].CellType = new CustomCell();
}

[Serializable]
public class CustomCell : FarPoint.Web.Spread.TextCellType
{
　　public override Control GetEditorControl(string id, System.Web.UI.WebControls.TableCell parent, FarPoint.Web.Spread.Appearance style, FarPoint.Web.Spread.Inset margin, object value, bool upperLevel)
　　{
　　　　// 既定の処理をコメントアウト
　　　　//return base.GetEditorControl(id, parent, style, margin, value, upperLevel);

　　　　// ReadOnlyに設定したTextBoxを編集時に使用
　　　　TextBox tb = base.GetEditorControl(id, parent, style, margin, value, upperLevel) as TextBox;
　　　　tb.Attributes["readonly"] = "readonly";
　　　　return tb;
　　}
}