Formatting a Value inside XAttribute

Question

I am trying to format a data bound item to just show three decimal points. It is inside a datatemplate written in the C# code. In wpf it was formatted like this

<TextBlock Grid.Column="1" Text="{Binding Path=[XValues], Converter={x:Static my:Converters.Format}, ConverterParameter=#.##}"/>

and in c# I have this so far

new XAttribute("Text", "{Binding Path=[XValues]}")

adding the Converter..... makes it fail at the x:

thanks