how to specify custom templating mechanism to a field template or if it is possible to do as follows to specify stackpanel?

<my:XamDataGrid Height="103" Margin="12,25,92,0" Name="xamDataGrid1" VerticalAlignment="Top" DataSource="{Binding Path=.}">

<my:XamDataGrid.FieldLayoutSettings>

<my:FieldLayoutSettings x:Uid="my:FieldLayoutSettings_1" AutoArrangeCells="Never" AutoGenerateFields="False" />

</my:XamDataGrid.FieldLayoutSettings>

<my:XamDataGrid.FieldLayouts>

<my:FieldLayout x:Uid="my:FieldLayout_1">

<my:FieldLayout.Fields>

<StackPanel><Label>Hello Description</Label><my:Field Name="appdesc" /> </StackPanel>

<my:Field Name="appdesccode"/>