How to bind to resource from codebehind without using DataContext

Question

I have a datagrid with messages, which has declared itemsource in codebehind. TO every row I need to add contextmenu from which user can select user to whom he wants forward a message.

<!-- COLUMN: DATE SENT -->
                    <data:DataGridTemplateColumn x:Name="DateSentColumn" CanUserSort="True"
                                             SortMemberPath="DateSent" Width="80">
                        <data:DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <TextBlock Text="{Binding DateSent, ConverterParameter=False, Converter={StaticResource cnvDate}}"
                                       ToolTipService.ToolTip="{Binding DateSent, ConverterParameter=True, Converter={StaticResource cnvDate}}"
                                       VerticalAlignment="Center"
                                       FontWeight="{Binding IsBold, Converter={StaticResource cnvFontWeight}}"
                                       Foreground="{Binding IsOverdueMessage, Converter={StaticResource cnvOverdue}}"
                                       Margin="5,0,5,0">

                                <telerik:RadContextMenu.ContextMenu>
                                    <telerik:RadContextMenu x:Name="inboxContextMenu" Opened="inboxContextMenu_Opened" ItemClick="inboxContextMenu_ItemClick">
                                        <telerik:RadMenuItem  x:Name="ForwardMessageMenuItem" Header="Forward message">
                                        <telerik:RadMenuItem  x:Name="SelectUserMenuItem"/>
                                        </telerik:RadMenuItem>
                                    </telerik:RadContextMenu>
                                </telerik:RadContextMenu.ContextMenu>
                                </TextBlock>
                            </DataTemplate>
                        </data:DataGridTemplateColumn.CellTemplate>

                    </data:DataGridTemplateColumn>

I don't know how can I bind users to SelectUserMenuItem radmenuitem.

In code behind I have a property Users.